PREFACE ...................................................... xiii
ACKNOWLEDGMENTS ................................................ xv
1 Introduction ................................................. 1
2 Description of Severe Plastic Deformation (SPD):
Principles and Techniques .................................... 6
2.1 A Historical Retrospective of SPD Processing ............ 6
2.2 Main Techniques for Severe Plastic Deformation .......... 8
2.3 SPD Processing Regimes for Grain Refinement ............ 15
2.4 Types of Nanostructures from SPD ....................... 16
PART ONE HIGH-PRESSURE TORSION ................................ 23
3 Principles and Technical Parameters of High-Pressure
Torsion ..................................................... 25
3.1 A History of High-Pressure Deformation ................. 25
3.2 Definition of the Strain Imposed in HPT ................ 28
3.3 Principles of Unconstrained and Constrained HPT ........ 32
3.4 Variation in Homogeneity Across an HPT Disk ............ 33
3.4.1 Developing a Pictorial Representation of the
Microhardness Distributions ..................... 33
3.4.2 Macroscopic Row Pattern During HPT .............. 38
3.4.3 Occurrence of Nonhomogeneity in the
Microstructures Produced by HPT ................. 52
3.5 Influence of Applied Load and Accumulated Strain on
Microstructural Evolution .............................. 67
3.6 Influence of Strain Hardening and Dynamic Recovery ..... 71
3.7 Significance of Slippage During High-Pressure
Torsioning ............................................. 76
3.8 Models for the Development of Homogeneity in HPT ....... 81
4 HPT Processing of Metals, Alloys, and Composites ............ 88
4.1 Microstructure Evolution and Grain Refinement in
Metals Subjected to HPT ................................ 88
4.1.1 Microstructure and Grain Refinement in fee and
bec Pure Metals ................................. 88
4.1.2 Allotropic Transformation in HCP Metals as
Mechanism of Grain Refinement ................... 97
4.1.3 Significance of the Minimum Grain Size
Attained Using HPT ............................. 103
4.1.4 Microtexture and Grain Boundary Statistics in
HPT Metals ..................................... 107
4.2 Processing of Solid Solutions and Multiphase Alloys ... 112
4.2.1 High-Pressure Torsion of Solid Solutions ....... 112
4.2.2 Grain Refinement During Processing of
Multiphase Alloys .............................. 119
4.2.3 Amorphization and Nanocrystallization of
Alloys by HPT .................................. 126
4.3 Processing of Intermetallics by HPT ................... 130
4.4 Processing of Metal Matrix Composites ................. 136
5 New Approaches to HPT Processing ........................... 152
5.1 Cyclic Processing by Reversing the Direction of
Torsional Straining ................................... 152
5.2 Using HPT for the Cold Consolidation of Powders and
Machining Chips ....................................... 173
5.3 Extension of HPT to Large Samples ..................... 180
PART TWO EQUAL CHANNEL ANGULAR PRESSING
6 Development of Processing Using Equal-Channel Angular
Pressing ................................................... 193
6.1 Construction of an ECAP/ECAE Facility ................. 193
6.2 Equal-Channel Angular Pressing of Rods, Bars, and
Plate Samples ......................................... 195
6.3 Alternative Procedures for Achieving ECAP: Rotary
Dies, Side-Extrusion, and Multipass Dies .............. 198
6.4 Developing ECAP with Parallel Channels ................ 201
6.5 Continuous Processing by ECAP: From Continuous
Confined Shearing, Equal-Channel Angular Drawing and
Conshearing, to Conform Process ....................... 204
7 Fundamental Parameters and Experimental Factors in ECAP .... 215
7.1 Strain Imposed in ECAP ................................ 215
7.2 Processing Routes in ECAP ............................. 219
7.3 Shearing Patterns Associated with ECAP ................ 221
7.4 Experimental Factors Influencing ECAP ................. 223
7.4.1 Influence of the Channel Angle and the Angle
of Curvature ................................... 223
7.4.2 Influence of the Pressing Speed and
Temperature .................................... 229
7.5 Role of Internal Heating During ECAP .................. 232
7.6 Influence of a Back Pressure .......................... 234
8 Grain Refinement in Metallic Systems Processed by ECAP ..... 239
8.1 Mesoscopic Characteristics After ECAP ................. 240
8.2 Development of an Ultrafine-Grained Microstructure .... 244
8.3 Factors Governing the Ultrafine Grain Size in ECAP .... 253
8.4 Microstructural Features and Texture After ECAP ....... 256
8.5 Influence of ECAP on Precipitation .................... 262
8.6 Pressing of Multiphase Alloys and Composites .......... 266
8.6.1 Multiphase Alloys .............................. 267
8.6.2 Metal Matrix Composites ........................ 270
8.7 Consolidation by ECAP ................................. 275
8.8 Post-ECAP Processing .................................. 277
PART THREE FUNDAMENTALS AND PROPERTIES OF MATERIALS AFTER
SPD ........................................................... 289
9 Structural Modeling and Physical Properties of
SPD-Processed Materials .................................... 291
9.1 Experimental Studies of Grain Boundaries in BNM ....... 293
9.2 Developments of Structural Model of BNM ............... 309
9.3 Fundamental Parameters and Physical Properties ........ 312
9.3.1 Curie Temperature and Magnetic Properties ...... 313
9.3.2 Debye Temperature and Diffusivity .............. 315
9.3.3 Electroconductivity ............................ 320
9.3.4 Elastic Properties and Internal Friction ....... 323
10 Mechanical Properties of BNM at Ambient Temperature ........ 331
10.1 Strength and "Superstrength" .......................... 332
10.2 Plastic Deformation and Ductility ..................... 338
10.3 Fatigue Behavior ...................................... 345
10.4 Alternative Deformation Mechanisms at Very Small
Grain Sizes ........................................... 350
11 Mechanical Properties at High Temperatures ................. 357
11.1 Achieving Superplasticity in Ultrafine-Grained
Metals ................................................ 359
11.1.1 Superplasticity after Processing by HPT ........ 360
11.1.2 Superplasticity after Processing by ECAP ....... 364
11.2 Effects of Different ECAP Processing Routes on
Superplasticity ....................................... 370
11.3 Developing a Superplastic Forming Capability .......... 375
11.4 Cavitation in Superplasticity After SPD ............... 378
11.5 Future Prospects for Superplasticity in
Nanostractured Materials .............................. 380
12 Functional and Multifunctional Properties of Bulk
Nanostructured Materials ................................... 387
12.1 Corrosion Behavior .................................... 388
12.2 Wear Resistance ....................................... 390
12.3 Enhanced Strength and Conductivity .................... 393
12.4 Biomedical Behavior of Nanometals ..................... 396
12.5 Enhanced Magnetic Properties .......................... 398
12.6 Inelasticity and Shape-Memory Effects ................. 402
12.7 Other Functional Properties ........................... 405
12.7.1 Enhanced Reaction Kinetics ..................... 405
12.7.2 Radiation Resistance ........................... 407
12.7.3 Thermoelectric Property ........................ 408
12.7.1 PART FOUR INNOVATION POTENTIAL AND PROSPECTS
FOR SPD APPLICATIONS ........................... 415
13 Innovation Potential of Bulk Nanostructured Materials ...... 417
13.1 Nanotitanium and Ti Alloys for Medical Implants ....... 417
13.2 Nanostructured Mg Alloys for Hydrogen Storage ......... 420
13.3 Micro-Devices from BNM ................................ 423
13.4 Innovation Potential and Application of
Nanostructured Al Alloys .............................. 423
13.5 Fabrication of Nanostructured Steels for Engineering .. 425
14 Conclusions ................................................ 434
Index ......................................................... 436
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