Hang Z. Yu, PhD, is an Associate Professor in the Department of Materials Science and Engineering at Virginia Tech, USA. His research focuses on materials processing and manufacturing science, emphasizing the underlying process physics, mechanics, and kinetics. His work also aims to leverage the process fundamentals to drive material sustainability to new heights, e.g., via solid-state metal recycling, structural repair, and austere condition-resilient manufacturing. Nihan Tuncer, PhD, is a Principal Scientist at Desktop Metal Inc. since 2016, where she has been developing solid-state 3D printing technologies and equipment. She holds several patents in addition to research papers and review articles. Her expertise includes powder metallurgy, processing-microstructure-property relationships in ferrous and non-ferrous alloys, porous metals, and shape memory alloys. Zhili Feng, PhD, currently leads the Materials Joining Group and is a Distinguished R&D Staff Member of Oak Ridge National Laboratory, USA. His research covers various aspects of thermal-mechanical-metallurgical behaviors of materials in materials joining.

• Preface xiiiPart I Introduction 11 Introduction and Overview 3Hang Z. Yu, Nihan Tuncer, and Zhili Feng1.1 Overview and History of Metal Additive Manufacturing 41.2 Liquid-State Bonding Versus Solid-State Bonding 71.2.1 Liquid-State Bonding 71.2.2 Solid-State Bonding 81.3 Nonbeam-Based, Solid-State Metal Additive Manufacturing 91.3.1 Deformation-Based Metal Additive Manufacturing 91.3.2 Sintering-Based Metal Additive Manufacturing 111.4 Additive Manufacturing Categorization Based on the Relationship Between Shape Forming and Consolidation 121.5 Organization of the Book 14References 15Part II Cold Spray Additive Manufacturing 192 Impact-Induced Bonding: Physical Processes and Bonding Mechanisms 21David Veysset and Mostafa Hassani2.1 Introduction 212.2 Fundamentals of Impact Bonding 232.2.1 Plate Impacts and Explosive Welding 232.2.1.1 The Shock Equations of State 232.2.1.2 Limiting Conditions for Explosive Welding 242.2.2 Laser Impact Bonding 302.3 Bonding Mechanisms in Cold Spray 322.3.1 Proposed Mechanisms 322.3.1.1 The Role of Jetting and Impact Pressure in Particle Bonding 322.3.1.2 The Limiting Case of Impact Melting 332.3.1.3 Adiabatic Shear Instability 362.3.1.4 Dissimilar Materials Impact 402.3.2 Influence of Particle Characteristics 412.3.2.1 Particle Temperature 412.3.2.2 Particle Size 422.3.2.3 Surface Oxide and Hydroxide Effects 42References 433 Microstructures and Microstructural Evolution in Cold-Sprayed Materials 49Luke N. Brewer and Lorena I. Perez-Andrade3.1 Introduction 493.2 Defect Structures 503.2.1 Vacancies 513.2.2 Dislocation Structure 523.2.3 Grain Structure 553.2.4 Precipitate Structure 563.2.5 Porosity 603.3 Microstructural Evolution of Thermally Treated Cold-Sprayed Materials 613.3.1 Recovery, Recrystallization, and Grain Growth 623.3.2 Precipitation 653.3.3 Heat Treatment of Feedstock Powders and its Impact on Microstructure 663.4 Conclusions 67Acknowledgements 67References 684 Mechanical Properties of Cold Spray Deposits 75Sara Bagherifard and Mario Guagliano4.1 Introduction 754.2 Mechanical Properties 764.2.1 Adhesive Strength 774.2.1.1 Adhesive Strength Test Methods 774.2.1.2 The Effect of Process Parameters on Adhesive Strength 804.2.1.3 The effect of Pre-/Post-treatments on Adhesive Strength 804.2.2 Cohesive Strength 834.2.2.1 Cohesive Strength Test methods 844.2.2.2 Cohesive Strength Under Static Loading 844.2.2.3 Cohesive Strength Under Fatigue Loading 864.2.2.4 Anisotropy in Cohesive Strength 904.2.3 Summary and Future Perspectives 91References 945 Cold Spray in Practical and Potential Applications 101Jingjie Wei, Yong He, Phuong Vo, and Yu Zou5.1 Introduction 1015.1.1 The Cold Spray Process 1015.1.2 Cold Spray Additive Manufacturing (CSAM) 1035.2 Materials 1035.2.1 Cu and Cu Alloys 1035.2.1.1 2Cu–Ga and Cu–In–Ga 1075.2.1.2 Cu–Sn 1075.2.1.3 Cu–W 1075.2.2 Al and Al Alloys 1085.2.3 Ni and Ni Alloys 1105.2.4 Stainless Steels 1115.2.5 Body Center Cubic (BCC) Metals 1125.2.5.1 Tantalum 1125.2.5.2 Niobium 1145.2.6 Hexagonal Close-Packed (HCP) Metals 1145.2.6.1 Titanium 1145.2.6.2 Magnesium 1165.2.7 Metal Mixes and Metal Matrix Composite (MMC) 1165.2.7.1 Metal Mixes 1175.2.7.2 Metal Matrix Composite 1175.2.8 Multicomponent and High Entropy Alloys 1205.2.8.1 MCrAlY Multicomponent Alloy 1205.2.8.2 High Entropy Alloy (HEA) 1205.2.9 Multimaterials 1215.3 Perspective and Challenges 122References 124Part III Additive Friction Stir Deposition 1336 Process Fundamentals of Additive Friction Stir Deposition 135David Garcia and Hang Z. Yu6.1 Additive Friction Stir Deposition – Macroscopic Process Overview 1366.2 Thermo-Mechanical Processing Evolution 1396.3 Heat Generation and Heat Transfer 1426.3.1 Heat Generation and Heat Transfer Mechanisms 1426.3.2 Peak Temperature and Material Dependence 1436.4 Material Flow and Deformation 146References 1497 Dynamic Microstructure Evolution in Additive Friction Stir Deposition 153Robert J. Griffiths and Hunter A. Rauch7.1 Introduction to Microstructure Evolution in Additive Friction Stir Deposition 1547.2 Dynamic Microstructure Evolution in Single-Phase Materials 1557.2.1 Stacking Fault Energy and Dislocation Mobility 1557.2.2 Dynamic Recovery 1577.2.3 Continuous Dynamic Recrystallization 1577.2.4 Discontinuous Dynamic Recrystallization 1597.2.5 Static and Post-Dynamic Recrystallization 1607.2.6 Heterogeneous Deposits and Metadynamic Recrystallization 1617.3 Dynamic Microstructure Evolution in Multiple-Phase Materials 1627.3.1 Thermal Evolution During Additive Friction Stir Deposition 1627.3.2 Evolution of Secondary Phases at Low Temperature 1647.3.3 Evolution of Secondary Phases at High Temperature 1667.3.4 Evolution of Secondary Phases After Deformation 1687.3.5 Mapping Secondary Phase Evolution to Processing Space 1687.4 Effects of Material Transport on Microstructure Evolution 1707.4.1 Mechanisms of Material Transport 1707.4.2 Material Transport for the Homogenization of Mixtures 1727.4.3 Densification of Material Through Material Transport 1737.4.4 Material Transport and Spatial Variance in Thermomechanical Conditions 1747.5 The Study of Microstructure Evolution in Additive Friction Stir Deposition 1757.5.1 Contemporary Approaches 1757.5.2 Novel Approaches 177Acknowledgement 177References 1778 Mechanical Properties of Additive Friction Stir Deposits 181Dustin Avery and Mackenzie Perry8.1 Introduction 1818.2 Magnesium-Based Alloys 1848.2.1 WE43 1848.2.2 AZ31 1878.3 Aluminum-Based Alloys 1898.3.1 5xxx 1908.3.2 2xxx 1928.3.3 6xxx 1938.3.4 7xxx 1958.3.5 Cast Al Alloys 1978.4 Other Alloys Systems 1978.4.1 Nickel-Based Alloys 1978.4.2 Copper-Based Alloys 1988.4.3 Titanium-Based Alloys 1988.4.4 Steel Alloys 1998.4.5 High-Entropy Alloys 1998.4.6 Metal Matrix Composites 2008.5 Repair 2008.6 Summary and Future Perspectives 2018.6.1 Anisotropy 2018.6.2 Graphite Lubricant 2028.6.3 Multimaterial or Designed Feedstock 2028.6.4 Effect of Process Parameters on Mechanical Properties 2028.6.5 Active Cooling/Heating 2028.6.6 Heat Treatment 2028.6.7 High-Temperature Materials – Tool Wear 2038.6.8 Unique Possibilities 2038.6.9 Modeling 203References 2039 Potential Industrial Applications of Additive Friction Stir Deposition 209Hang Z. Yu, Rajiv S. Mishra, Chase D. Cox, and Zhili Feng9.1 Large-Scale Metal Additive Manufacturing 2099.2 Selective Area Cladding 2119.3 Recycling and Upcycling 2149.4 Structural Repair 2209.5 Underwater Deposition 224Acknowledgment 227References 227Part IV Ultrasonic Additive Manufacturing 23110 Process Fundamentals of Ultrasonic Additive Manufacturing 233Austin Ward10.1 Process Overview 23310.1.1 Process Parameters 23410.2 Temperature Rise and Thermal Modeling 23510.2.1 Heat Generation During Welding 23510.2.2 Sonotrode Contact Stress 23710.2.3 Coefficient of Friction 23810.2.4 Temperature Profile 23910.3 Feedstock Bonding Mechanisms 24110.3.1 Oxide Breakdown 24110.3.2 Asperity Deformation 24310.3.3 Diffusional Bonding Processes 24610.3.4 Liquid-Phase Bonding 24710.4 Dissimilar Metal Consolidation 24710.4.1 Mechanical and Thermal Modeling 24710.4.2 Dissimilar Metal Junction Growth 24810.4.3 Interdiffusion 24910.5 Acoustic Softening and Strain Normality 25110.5.1 Cyclic Strain Ratcheting 25310.6 Summary 254Acknowledgments 255References 25511 Ultrasonic Additive Manufacturing: Microstructural and Mechanical Characterization 259Tianyang (Tyler) Han, Leon M. Headings, and Marcelo J. Dapino11.1 Introduction 25911.2 Microstructure Analysis of UAM Builds 25911.2.1 Similar Material Joining with UAM 26011.2.2 Dissimilar Material Joining with UAM 26211.2.2.1 Al-Ceramic Weld 26211.2.2.2 Ni-Steel Weld 26311.3 Hardness Analysis of UAM Builds 26611.4 Mechanical Characterization of UAM Builds 26711.4.1 Design of a Custom Shear Testing Method 26811.4.2 Validation of the Shear Test 26811.4.3 Finite element Modeling of the Shear Test 27011.4.4 Application of the Shear Test to UAM Samples 27311.5 Conclusions 275References 27512 Industrial Applications of Ultrasonic Additive Manufacturing 279Mark Norfolk12.1 Early Years 27912.2 Increased Power → Increased Capability 28112.3 Modern Applications 28212.3.1 Electrification 28212.3.2 Thermal Management 28612.3.3 Embedded Electronics 28812.3.3.1 SmartPlate 29012.3.3.2 SensePipe 29112.4 Future Applications 292References 292Part V Sintering-Based Processes 29513 Principles of Solid-State Sintering 297Basil J. Paudel, Albert C. To, and Amir Mostafaei13.1 Introduction 29713.2 Basic Terminology 29813.2.1 Sintering 29813.2.2 Relative Density/Green Density 29913.2.3 Coordination Number 29913.2.4 Surface Tension/Surface Energy 30013.2.5 Wetting Angle/Dihedral Angle 30013.2.6 Neck Growth/Shrinkage/Densification 30113.3 Sintering Stress 30213.3.1 Two Particle Model 30213.3.1.1 Case I: Without Shrinkage 30313.3.1.2 Case II: With Shrinkage 30313.3.2 Driving Force 30313.3.3 Interfacial Activity/Thermodynamics 30413.4 Mass Transport Mechanisms 30613.4.1 Grain Boundary Diffusion 30613.4.2 Lattice/Volume Diffusion 30613.4.3 Viscous Flow 30613.4.4 Surface Diffusion 30713.4.5 Evaporation/Condensation 30713.4.6 Gas Diffusion 30713.5 Sintering Stages 30713.6 Sintering Simulation 30813.7 Concluding Remarks, Challenges, and Future Works 309References 31014 Material Extrusion Additive Manufacturing 313Alexander C. Barbati and Aaron Preston14.1 Introduction 31314.2 Hierarchy of MEAM Parts and Feedstock Behavior 31614.3 Feedstock Attributes 32514.4 Extrusion Control 32714.5 Toolpathing: Strength and Quality 33114.6 Conclusions 335Acknowledgments 336References 33615 Binder Jetting-based Metal Printing 339Marco Mariani, Nora Lecis, and Amir Mostafaei15.1 Introduction to Binder Jetting 33915.2 Printing Phase 34115.2.1 Particulate Feedstock 34115.2.1.1 Feedstock Materials 34215.2.1.2 Feedstock Morphology and Size Distribution 34315.2.2 Binder Selection 34415.2.3 Powder Spreading and Binder Deposition System Configurations 34515.3 Thermal Treatments 34615.3.1 Curing 34615.3.2 Debinding 34715.3.3 Sintering 34815.3.4 Additional Treatments 34915.4 Future Developments 35015.5 Conclusion 352References 35216 Sintering-based Metal Additive Manufacturing Methods for Magnetic Materials 361H. Wang, A. M. Elliot, and M. P. Paranthaman16.1 Introduction 36116.2 Background 36216.3 Additive Manufacturing Methods 36916.4 Applications 37216.5 Summary 374Acknowledgments 375References 37517 Future Perspectives 379Hang Z. Yu, Nihan Tuncer, and Zhili Feng17.1 Enhancing the Understanding of Process Fundamentals 37917.2 Expanding the Printable Material Library 38117.3 Embracing Artificial Intelligence for Quality Control and Process Prediction 381References 383Index 385

Hang Z. Yu, PhD, is an Associate Professor in the Department of Materials Science and Engineering at Virginia Tech, USA. His research focuses on materials processing and manufacturing science, emphasizing the underlying process physics, mechanics, and kinetics. His work also aims to leverage the process fundamentals to drive material sustainability to new heights, e.g., via solid-state metal recycling, structural repair, and austere condition-resilient manufacturing. Nihan Tuncer, PhD, is a Principal Scientist at Desktop Metal Inc. since 2016, where she has been developing solid-state 3D printing technologies and equipment. She holds several patents in addition to research papers and review articles. Her expertise includes powder metallurgy, processing-microstructure-property relationships in ferrous and non-ferrous alloys, porous metals, and shape memory alloys. Zhili Feng, PhD, currently leads the Materials Joining Group and is a Distinguished R&D Staff Member of Oak Ridge National Laboratory, USA. His research covers various aspects of thermal-mechanical-metallurgical behaviors of materials in materials joining.

• Preface xiiiPart I Introduction 11 Introduction and Overview 3Hang Z. Yu, Nihan Tuncer, and Zhili Feng1.1 Overview and History of Metal Additive Manufacturing 41.2 Liquid-State Bonding Versus Solid-State Bonding 71.2.1 Liquid-State Bonding 71.2.2 Solid-State Bonding 81.3 Nonbeam-Based, Solid-State Metal Additive Manufacturing 91.3.1 Deformation-Based Metal Additive Manufacturing 91.3.2 Sintering-Based Metal Additive Manufacturing 111.4 Additive Manufacturing Categorization Based on the Relationship Between Shape Forming and Consolidation 121.5 Organization of the Book 14References 15Part II Cold Spray Additive Manufacturing 192 Impact-Induced Bonding: Physical Processes and Bonding Mechanisms 21David Veysset and Mostafa Hassani2.1 Introduction 212.2 Fundamentals of Impact Bonding 232.2.1 Plate Impacts and Explosive Welding 232.2.1.1 The Shock Equations of State 232.2.1.2 Limiting Conditions for Explosive Welding 242.2.2 Laser Impact Bonding 302.3 Bonding Mechanisms in Cold Spray 322.3.1 Proposed Mechanisms 322.3.1.1 The Role of Jetting and Impact Pressure in Particle Bonding 322.3.1.2 The Limiting Case of Impact Melting 332.3.1.3 Adiabatic Shear Instability 362.3.1.4 Dissimilar Materials Impact 402.3.2 Influence of Particle Characteristics 412.3.2.1 Particle Temperature 412.3.2.2 Particle Size 422.3.2.3 Surface Oxide and Hydroxide Effects 42References 433 Microstructures and Microstructural Evolution in Cold-Sprayed Materials 49Luke N. Brewer and Lorena I. Perez-Andrade3.1 Introduction 493.2 Defect Structures 503.2.1 Vacancies 513.2.2 Dislocation Structure 523.2.3 Grain Structure 553.2.4 Precipitate Structure 563.2.5 Porosity 603.3 Microstructural Evolution of Thermally Treated Cold-Sprayed Materials 613.3.1 Recovery, Recrystallization, and Grain Growth 623.3.2 Precipitation 653.3.3 Heat Treatment of Feedstock Powders and its Impact on Microstructure 663.4 Conclusions 67Acknowledgements 67References 684 Mechanical Properties of Cold Spray Deposits 75Sara Bagherifard and Mario Guagliano4.1 Introduction 754.2 Mechanical Properties 764.2.1 Adhesive Strength 774.2.1.1 Adhesive Strength Test Methods 774.2.1.2 The Effect of Process Parameters on Adhesive Strength 804.2.1.3 The effect of Pre-/Post-treatments on Adhesive Strength 804.2.2 Cohesive Strength 834.2.2.1 Cohesive Strength Test methods 844.2.2.2 Cohesive Strength Under Static Loading 844.2.2.3 Cohesive Strength Under Fatigue Loading 864.2.2.4 Anisotropy in Cohesive Strength 904.2.3 Summary and Future Perspectives 91References 945 Cold Spray in Practical and Potential Applications 101Jingjie Wei, Yong He, Phuong Vo, and Yu Zou5.1 Introduction 1015.1.1 The Cold Spray Process 1015.1.2 Cold Spray Additive Manufacturing (CSAM) 1035.2 Materials 1035.2.1 Cu and Cu Alloys 1035.2.1.1 2Cu–Ga and Cu–In–Ga 1075.2.1.2 Cu–Sn 1075.2.1.3 Cu–W 1075.2.2 Al and Al Alloys 1085.2.3 Ni and Ni Alloys 1105.2.4 Stainless Steels 1115.2.5 Body Center Cubic (BCC) Metals 1125.2.5.1 Tantalum 1125.2.5.2 Niobium 1145.2.6 Hexagonal Close-Packed (HCP) Metals 1145.2.6.1 Titanium 1145.2.6.2 Magnesium 1165.2.7 Metal Mixes and Metal Matrix Composite (MMC) 1165.2.7.1 Metal Mixes 1175.2.7.2 Metal Matrix Composite 1175.2.8 Multicomponent and High Entropy Alloys 1205.2.8.1 MCrAlY Multicomponent Alloy 1205.2.8.2 High Entropy Alloy (HEA) 1205.2.9 Multimaterials 1215.3 Perspective and Challenges 122References 124Part III Additive Friction Stir Deposition 1336 Process Fundamentals of Additive Friction Stir Deposition 135David Garcia and Hang Z. Yu6.1 Additive Friction Stir Deposition – Macroscopic Process Overview 1366.2 Thermo-Mechanical Processing Evolution 1396.3 Heat Generation and Heat Transfer 1426.3.1 Heat Generation and Heat Transfer Mechanisms 1426.3.2 Peak Temperature and Material Dependence 1436.4 Material Flow and Deformation 146References 1497 Dynamic Microstructure Evolution in Additive Friction Stir Deposition 153Robert J. Griffiths and Hunter A. Rauch7.1 Introduction to Microstructure Evolution in Additive Friction Stir Deposition 1547.2 Dynamic Microstructure Evolution in Single-Phase Materials 1557.2.1 Stacking Fault Energy and Dislocation Mobility 1557.2.2 Dynamic Recovery 1577.2.3 Continuous Dynamic Recrystallization 1577.2.4 Discontinuous Dynamic Recrystallization 1597.2.5 Static and Post-Dynamic Recrystallization 1607.2.6 Heterogeneous Deposits and Metadynamic Recrystallization 1617.3 Dynamic Microstructure Evolution in Multiple-Phase Materials 1627.3.1 Thermal Evolution During Additive Friction Stir Deposition 1627.3.2 Evolution of Secondary Phases at Low Temperature 1647.3.3 Evolution of Secondary Phases at High Temperature 1667.3.4 Evolution of Secondary Phases After Deformation 1687.3.5 Mapping Secondary Phase Evolution to Processing Space 1687.4 Effects of Material Transport on Microstructure Evolution 1707.4.1 Mechanisms of Material Transport 1707.4.2 Material Transport for the Homogenization of Mixtures 1727.4.3 Densification of Material Through Material Transport 1737.4.4 Material Transport and Spatial Variance in Thermomechanical Conditions 1747.5 The Study of Microstructure Evolution in Additive Friction Stir Deposition 1757.5.1 Contemporary Approaches 1757.5.2 Novel Approaches 177Acknowledgement 177References 1778 Mechanical Properties of Additive Friction Stir Deposits 181Dustin Avery and Mackenzie Perry8.1 Introduction 1818.2 Magnesium-Based Alloys 1848.2.1 WE43 1848.2.2 AZ31 1878.3 Aluminum-Based Alloys 1898.3.1 5xxx 1908.3.2 2xxx 1928.3.3 6xxx 1938.3.4 7xxx 1958.3.5 Cast Al Alloys 1978.4 Other Alloys Systems 1978.4.1 Nickel-Based Alloys 1978.4.2 Copper-Based Alloys 1988.4.3 Titanium-Based Alloys 1988.4.4 Steel Alloys 1998.4.5 High-Entropy Alloys 1998.4.6 Metal Matrix Composites 2008.5 Repair 2008.6 Summary and Future Perspectives 2018.6.1 Anisotropy 2018.6.2 Graphite Lubricant 2028.6.3 Multimaterial or Designed Feedstock 2028.6.4 Effect of Process Parameters on Mechanical Properties 2028.6.5 Active Cooling/Heating 2028.6.6 Heat Treatment 2028.6.7 High-Temperature Materials – Tool Wear 2038.6.8 Unique Possibilities 2038.6.9 Modeling 203References 2039 Potential Industrial Applications of Additive Friction Stir Deposition 209Hang Z. Yu, Rajiv S. Mishra, Chase D. Cox, and Zhili Feng9.1 Large-Scale Metal Additive Manufacturing 2099.2 Selective Area Cladding 2119.3 Recycling and Upcycling 2149.4 Structural Repair 2209.5 Underwater Deposition 224Acknowledgment 227References 227Part IV Ultrasonic Additive Manufacturing 23110 Process Fundamentals of Ultrasonic Additive Manufacturing 233Austin Ward10.1 Process Overview 23310.1.1 Process Parameters 23410.2 Temperature Rise and Thermal Modeling 23510.2.1 Heat Generation During Welding 23510.2.2 Sonotrode Contact Stress 23710.2.3 Coefficient of Friction 23810.2.4 Temperature Profile 23910.3 Feedstock Bonding Mechanisms 24110.3.1 Oxide Breakdown 24110.3.2 Asperity Deformation 24310.3.3 Diffusional Bonding Processes 24610.3.4 Liquid-Phase Bonding 24710.4 Dissimilar Metal Consolidation 24710.4.1 Mechanical and Thermal Modeling 24710.4.2 Dissimilar Metal Junction Growth 24810.4.3 Interdiffusion 24910.5 Acoustic Softening and Strain Normality 25110.5.1 Cyclic Strain Ratcheting 25310.6 Summary 254Acknowledgments 255References 25511 Ultrasonic Additive Manufacturing: Microstructural and Mechanical Characterization 259Tianyang (Tyler) Han, Leon M. Headings, and Marcelo J. Dapino11.1 Introduction 25911.2 Microstructure Analysis of UAM Builds 25911.2.1 Similar Material Joining with UAM 26011.2.2 Dissimilar Material Joining with UAM 26211.2.2.1 Al-Ceramic Weld 26211.2.2.2 Ni-Steel Weld 26311.3 Hardness Analysis of UAM Builds 26611.4 Mechanical Characterization of UAM Builds 26711.4.1 Design of a Custom Shear Testing Method 26811.4.2 Validation of the Shear Test 26811.4.3 Finite element Modeling of the Shear Test 27011.4.4 Application of the Shear Test to UAM Samples 27311.5 Conclusions 275References 27512 Industrial Applications of Ultrasonic Additive Manufacturing 279Mark Norfolk12.1 Early Years 27912.2 Increased Power → Increased Capability 28112.3 Modern Applications 28212.3.1 Electrification 28212.3.2 Thermal Management 28612.3.3 Embedded Electronics 28812.3.3.1 SmartPlate 29012.3.3.2 SensePipe 29112.4 Future Applications 292References 292Part V Sintering-Based Processes 29513 Principles of Solid-State Sintering 297Basil J. Paudel, Albert C. To, and Amir Mostafaei13.1 Introduction 29713.2 Basic Terminology 29813.2.1 Sintering 29813.2.2 Relative Density/Green Density 29913.2.3 Coordination Number 29913.2.4 Surface Tension/Surface Energy 30013.2.5 Wetting Angle/Dihedral Angle 30013.2.6 Neck Growth/Shrinkage/Densification 30113.3 Sintering Stress 30213.3.1 Two Particle Model 30213.3.1.1 Case I: Without Shrinkage 30313.3.1.2 Case II: With Shrinkage 30313.3.2 Driving Force 30313.3.3 Interfacial Activity/Thermodynamics 30413.4 Mass Transport Mechanisms 30613.4.1 Grain Boundary Diffusion 30613.4.2 Lattice/Volume Diffusion 30613.4.3 Viscous Flow 30613.4.4 Surface Diffusion 30713.4.5 Evaporation/Condensation 30713.4.6 Gas Diffusion 30713.5 Sintering Stages 30713.6 Sintering Simulation 30813.7 Concluding Remarks, Challenges, and Future Works 309References 31014 Material Extrusion Additive Manufacturing 313Alexander C. Barbati and Aaron Preston14.1 Introduction 31314.2 Hierarchy of MEAM Parts and Feedstock Behavior 31614.3 Feedstock Attributes 32514.4 Extrusion Control 32714.5 Toolpathing: Strength and Quality 33114.6 Conclusions 335Acknowledgments 336References 33615 Binder Jetting-based Metal Printing 339Marco Mariani, Nora Lecis, and Amir Mostafaei15.1 Introduction to Binder Jetting 33915.2 Printing Phase 34115.2.1 Particulate Feedstock 34115.2.1.1 Feedstock Materials 34215.2.1.2 Feedstock Morphology and Size Distribution 34315.2.2 Binder Selection 34415.2.3 Powder Spreading and Binder Deposition System Configurations 34515.3 Thermal Treatments 34615.3.1 Curing 34615.3.2 Debinding 34715.3.3 Sintering 34815.3.4 Additional Treatments 34915.4 Future Developments 35015.5 Conclusion 352References 35216 Sintering-based Metal Additive Manufacturing Methods for Magnetic Materials 361H. Wang, A. M. Elliot, and M. P. Paranthaman16.1 Introduction 36116.2 Background 36216.3 Additive Manufacturing Methods 36916.4 Applications 37216.5 Summary 374Acknowledgments 375References 37517 Future Perspectives 379Hang Z. Yu, Nihan Tuncer, and Zhili Feng17.1 Enhancing the Understanding of Process Fundamentals 37917.2 Expanding the Printable Material Library 38117.3 Embracing Artificial Intelligence for Quality Control and Process Prediction 381References 383Index 385

Hang Z. Yu, PhD, is an Associate Professor in the Department of Materials Science and Engineering at Virginia Tech, USA. His research focuses on materials processing and manufacturing science, emphasizing the underlying process physics, mechanics, and kinetics. His work also aims to leverage the process fundamentals to drive material sustainability to new heights, e.g., via solid-state metal recycling, structural repair, and austere condition-resilient manufacturing. Nihan Tuncer, PhD, is a Principal Scientist at Desktop Metal Inc. since 2016, where she has been developing solid-state 3D printing technologies and equipment. She holds several patents in addition to research papers and review articles. Her expertise includes powder metallurgy, processing-microstructure-property relationships in ferrous and non-ferrous alloys, porous metals, and shape memory alloys. Zhili Feng, PhD, currently leads the Materials Joining Group and is a Distinguished R&D Staff Member of Oak Ridge National Laboratory, USA. His research covers various aspects of thermal-mechanical-metallurgical behaviors of materials in materials joining.

• Preface xiiiPart I Introduction 11 Introduction and Overview 3Hang Z. Yu, Nihan Tuncer, and Zhili Feng1.1 Overview and History of Metal Additive Manufacturing 41.2 Liquid-State Bonding Versus Solid-State Bonding 71.2.1 Liquid-State Bonding 71.2.2 Solid-State Bonding 81.3 Nonbeam-Based, Solid-State Metal Additive Manufacturing 91.3.1 Deformation-Based Metal Additive Manufacturing 91.3.2 Sintering-Based Metal Additive Manufacturing 111.4 Additive Manufacturing Categorization Based on the Relationship Between Shape Forming and Consolidation 121.5 Organization of the Book 14References 15Part II Cold Spray Additive Manufacturing 192 Impact-Induced Bonding: Physical Processes and Bonding Mechanisms 21David Veysset and Mostafa Hassani2.1 Introduction 212.2 Fundamentals of Impact Bonding 232.2.1 Plate Impacts and Explosive Welding 232.2.1.1 The Shock Equations of State 232.2.1.2 Limiting Conditions for Explosive Welding 242.2.2 Laser Impact Bonding 302.3 Bonding Mechanisms in Cold Spray 322.3.1 Proposed Mechanisms 322.3.1.1 The Role of Jetting and Impact Pressure in Particle Bonding 322.3.1.2 The Limiting Case of Impact Melting 332.3.1.3 Adiabatic Shear Instability 362.3.1.4 Dissimilar Materials Impact 402.3.2 Influence of Particle Characteristics 412.3.2.1 Particle Temperature 412.3.2.2 Particle Size 422.3.2.3 Surface Oxide and Hydroxide Effects 42References 433 Microstructures and Microstructural Evolution in Cold-Sprayed Materials 49Luke N. Brewer and Lorena I. Perez-Andrade3.1 Introduction 493.2 Defect Structures 503.2.1 Vacancies 513.2.2 Dislocation Structure 523.2.3 Grain Structure 553.2.4 Precipitate Structure 563.2.5 Porosity 603.3 Microstructural Evolution of Thermally Treated Cold-Sprayed Materials 613.3.1 Recovery, Recrystallization, and Grain Growth 623.3.2 Precipitation 653.3.3 Heat Treatment of Feedstock Powders and its Impact on Microstructure 663.4 Conclusions 67Acknowledgements 67References 684 Mechanical Properties of Cold Spray Deposits 75Sara Bagherifard and Mario Guagliano4.1 Introduction 754.2 Mechanical Properties 764.2.1 Adhesive Strength 774.2.1.1 Adhesive Strength Test Methods 774.2.1.2 The Effect of Process Parameters on Adhesive Strength 804.2.1.3 The effect of Pre-/Post-treatments on Adhesive Strength 804.2.2 Cohesive Strength 834.2.2.1 Cohesive Strength Test methods 844.2.2.2 Cohesive Strength Under Static Loading 844.2.2.3 Cohesive Strength Under Fatigue Loading 864.2.2.4 Anisotropy in Cohesive Strength 904.2.3 Summary and Future Perspectives 91References 945 Cold Spray in Practical and Potential Applications 101Jingjie Wei, Yong He, Phuong Vo, and Yu Zou5.1 Introduction 1015.1.1 The Cold Spray Process 1015.1.2 Cold Spray Additive Manufacturing (CSAM) 1035.2 Materials 1035.2.1 Cu and Cu Alloys 1035.2.1.1 2Cu–Ga and Cu–In–Ga 1075.2.1.2 Cu–Sn 1075.2.1.3 Cu–W 1075.2.2 Al and Al Alloys 1085.2.3 Ni and Ni Alloys 1105.2.4 Stainless Steels 1115.2.5 Body Center Cubic (BCC) Metals 1125.2.5.1 Tantalum 1125.2.5.2 Niobium 1145.2.6 Hexagonal Close-Packed (HCP) Metals 1145.2.6.1 Titanium 1145.2.6.2 Magnesium 1165.2.7 Metal Mixes and Metal Matrix Composite (MMC) 1165.2.7.1 Metal Mixes 1175.2.7.2 Metal Matrix Composite 1175.2.8 Multicomponent and High Entropy Alloys 1205.2.8.1 MCrAlY Multicomponent Alloy 1205.2.8.2 High Entropy Alloy (HEA) 1205.2.9 Multimaterials 1215.3 Perspective and Challenges 122References 124Part III Additive Friction Stir Deposition 1336 Process Fundamentals of Additive Friction Stir Deposition 135David Garcia and Hang Z. Yu6.1 Additive Friction Stir Deposition – Macroscopic Process Overview 1366.2 Thermo-Mechanical Processing Evolution 1396.3 Heat Generation and Heat Transfer 1426.3.1 Heat Generation and Heat Transfer Mechanisms 1426.3.2 Peak Temperature and Material Dependence 1436.4 Material Flow and Deformation 146References 1497 Dynamic Microstructure Evolution in Additive Friction Stir Deposition 153Robert J. Griffiths and Hunter A. Rauch7.1 Introduction to Microstructure Evolution in Additive Friction Stir Deposition 1547.2 Dynamic Microstructure Evolution in Single-Phase Materials 1557.2.1 Stacking Fault Energy and Dislocation Mobility 1557.2.2 Dynamic Recovery 1577.2.3 Continuous Dynamic Recrystallization 1577.2.4 Discontinuous Dynamic Recrystallization 1597.2.5 Static and Post-Dynamic Recrystallization 1607.2.6 Heterogeneous Deposits and Metadynamic Recrystallization 1617.3 Dynamic Microstructure Evolution in Multiple-Phase Materials 1627.3.1 Thermal Evolution During Additive Friction Stir Deposition 1627.3.2 Evolution of Secondary Phases at Low Temperature 1647.3.3 Evolution of Secondary Phases at High Temperature 1667.3.4 Evolution of Secondary Phases After Deformation 1687.3.5 Mapping Secondary Phase Evolution to Processing Space 1687.4 Effects of Material Transport on Microstructure Evolution 1707.4.1 Mechanisms of Material Transport 1707.4.2 Material Transport for the Homogenization of Mixtures 1727.4.3 Densification of Material Through Material Transport 1737.4.4 Material Transport and Spatial Variance in Thermomechanical Conditions 1747.5 The Study of Microstructure Evolution in Additive Friction Stir Deposition 1757.5.1 Contemporary Approaches 1757.5.2 Novel Approaches 177Acknowledgement 177References 1778 Mechanical Properties of Additive Friction Stir Deposits 181Dustin Avery and Mackenzie Perry8.1 Introduction 1818.2 Magnesium-Based Alloys 1848.2.1 WE43 1848.2.2 AZ31 1878.3 Aluminum-Based Alloys 1898.3.1 5xxx 1908.3.2 2xxx 1928.3.3 6xxx 1938.3.4 7xxx 1958.3.5 Cast Al Alloys 1978.4 Other Alloys Systems 1978.4.1 Nickel-Based Alloys 1978.4.2 Copper-Based Alloys 1988.4.3 Titanium-Based Alloys 1988.4.4 Steel Alloys 1998.4.5 High-Entropy Alloys 1998.4.6 Metal Matrix Composites 2008.5 Repair 2008.6 Summary and Future Perspectives 2018.6.1 Anisotropy 2018.6.2 Graphite Lubricant 2028.6.3 Multimaterial or Designed Feedstock 2028.6.4 Effect of Process Parameters on Mechanical Properties 2028.6.5 Active Cooling/Heating 2028.6.6 Heat Treatment 2028.6.7 High-Temperature Materials – Tool Wear 2038.6.8 Unique Possibilities 2038.6.9 Modeling 203References 2039 Potential Industrial Applications of Additive Friction Stir Deposition 209Hang Z. Yu, Rajiv S. Mishra, Chase D. Cox, and Zhili Feng9.1 Large-Scale Metal Additive Manufacturing 2099.2 Selective Area Cladding 2119.3 Recycling and Upcycling 2149.4 Structural Repair 2209.5 Underwater Deposition 224Acknowledgment 227References 227Part IV Ultrasonic Additive Manufacturing 23110 Process Fundamentals of Ultrasonic Additive Manufacturing 233Austin Ward10.1 Process Overview 23310.1.1 Process Parameters 23410.2 Temperature Rise and Thermal Modeling 23510.2.1 Heat Generation During Welding 23510.2.2 Sonotrode Contact Stress 23710.2.3 Coefficient of Friction 23810.2.4 Temperature Profile 23910.3 Feedstock Bonding Mechanisms 24110.3.1 Oxide Breakdown 24110.3.2 Asperity Deformation 24310.3.3 Diffusional Bonding Processes 24610.3.4 Liquid-Phase Bonding 24710.4 Dissimilar Metal Consolidation 24710.4.1 Mechanical and Thermal Modeling 24710.4.2 Dissimilar Metal Junction Growth 24810.4.3 Interdiffusion 24910.5 Acoustic Softening and Strain Normality 25110.5.1 Cyclic Strain Ratcheting 25310.6 Summary 254Acknowledgments 255References 25511 Ultrasonic Additive Manufacturing: Microstructural and Mechanical Characterization 259Tianyang (Tyler) Han, Leon M. Headings, and Marcelo J. Dapino11.1 Introduction 25911.2 Microstructure Analysis of UAM Builds 25911.2.1 Similar Material Joining with UAM 26011.2.2 Dissimilar Material Joining with UAM 26211.2.2.1 Al-Ceramic Weld 26211.2.2.2 Ni-Steel Weld 26311.3 Hardness Analysis of UAM Builds 26611.4 Mechanical Characterization of UAM Builds 26711.4.1 Design of a Custom Shear Testing Method 26811.4.2 Validation of the Shear Test 26811.4.3 Finite element Modeling of the Shear Test 27011.4.4 Application of the Shear Test to UAM Samples 27311.5 Conclusions 275References 27512 Industrial Applications of Ultrasonic Additive Manufacturing 279Mark Norfolk12.1 Early Years 27912.2 Increased Power → Increased Capability 28112.3 Modern Applications 28212.3.1 Electrification 28212.3.2 Thermal Management 28612.3.3 Embedded Electronics 28812.3.3.1 SmartPlate 29012.3.3.2 SensePipe 29112.4 Future Applications 292References 292Part V Sintering-Based Processes 29513 Principles of Solid-State Sintering 297Basil J. Paudel, Albert C. To, and Amir Mostafaei13.1 Introduction 29713.2 Basic Terminology 29813.2.1 Sintering 29813.2.2 Relative Density/Green Density 29913.2.3 Coordination Number 29913.2.4 Surface Tension/Surface Energy 30013.2.5 Wetting Angle/Dihedral Angle 30013.2.6 Neck Growth/Shrinkage/Densification 30113.3 Sintering Stress 30213.3.1 Two Particle Model 30213.3.1.1 Case I: Without Shrinkage 30313.3.1.2 Case II: With Shrinkage 30313.3.2 Driving Force 30313.3.3 Interfacial Activity/Thermodynamics 30413.4 Mass Transport Mechanisms 30613.4.1 Grain Boundary Diffusion 30613.4.2 Lattice/Volume Diffusion 30613.4.3 Viscous Flow 30613.4.4 Surface Diffusion 30713.4.5 Evaporation/Condensation 30713.4.6 Gas Diffusion 30713.5 Sintering Stages 30713.6 Sintering Simulation 30813.7 Concluding Remarks, Challenges, and Future Works 309References 31014 Material Extrusion Additive Manufacturing 313Alexander C. Barbati and Aaron Preston14.1 Introduction 31314.2 Hierarchy of MEAM Parts and Feedstock Behavior 31614.3 Feedstock Attributes 32514.4 Extrusion Control 32714.5 Toolpathing: Strength and Quality 33114.6 Conclusions 335Acknowledgments 336References 33615 Binder Jetting-based Metal Printing 339Marco Mariani, Nora Lecis, and Amir Mostafaei15.1 Introduction to Binder Jetting 33915.2 Printing Phase 34115.2.1 Particulate Feedstock 34115.2.1.1 Feedstock Materials 34215.2.1.2 Feedstock Morphology and Size Distribution 34315.2.2 Binder Selection 34415.2.3 Powder Spreading and Binder Deposition System Configurations 34515.3 Thermal Treatments 34615.3.1 Curing 34615.3.2 Debinding 34715.3.3 Sintering 34815.3.4 Additional Treatments 34915.4 Future Developments 35015.5 Conclusion 352References 35216 Sintering-based Metal Additive Manufacturing Methods for Magnetic Materials 361H. Wang, A. M. Elliot, and M. P. Paranthaman16.1 Introduction 36116.2 Background 36216.3 Additive Manufacturing Methods 36916.4 Applications 37216.5 Summary 374Acknowledgments 375References 37517 Future Perspectives 379Hang Z. Yu, Nihan Tuncer, and Zhili Feng17.1 Enhancing the Understanding of Process Fundamentals 37917.2 Expanding the Printable Material Library 38117.3 Embracing Artificial Intelligence for Quality Control and Process Prediction 381References 383Index 385