Gamma Titanium Aluminide Alloys Science and Technology

This first book entirely dedicated to titanium aluminide alloys emphasizes the relation between basic research topics and processing technologies for real applications. As such, it covers complex microstructures down to the nanometer scale, titanium aluminide structure/property relationships and the potential in such key industries as aerospace, automotive and power conversion. The result is more detailed coverage of the fundamentals than is otherwise found in typical textbooks, making this relevant reading not only for the Ti-Al research community, but also for a wide range of physical metallurgists, product developers and industrial companies needing advanced, lightweight metallic components.

Fritz Appel has continued to play an active role in TiAl research since his retirement in 2006 as group leader of physical metallurgy. He obtained his Ph.D. in 1973 and his habilitation in 1987 from the Martin-Luther University in Halle, Germany. He spent six months in Japan on a JSPS fellowship in 1987, joining the GKSS Research Center in Geesthacht in 1990. Dr. Appel received the Tammann Award from the German Society for Materials Science in 1999 and the Charles Hatchett Award in 2002 from the Institute of Materials, London. He has published over 160 papers, given over 80 invited lectures and holds six patents in the field.

Jonathan Paul has been a member of the Institute of Materials Research in Geesthacht since 1999. He obtained his Ph.D. from Manchester University in 1990, and after a year of postdoctoral research, moved to the Commissariat ? l'?nergie Atomique at Saclay in 1993. Between 1995 and 1997 he worked as a research fellow at GKSS, before being employed at the Defence Evaluation Research Agency (formerly known as the Royal Aircraft Establishment, now re-named QinetiQ) within the Structural Materials Centre in Farnborough. Dr. Paul received the Vanadium Award in 1995 and the Charles Hatchett Award in 2002, both from the Institute of Materials, London. He has co-authored and authored a number of publications and holds four patents.

Michael Oehring works in the physical metallurgy group at the Institute of Materials Research in Geesthacht. He received his Ph.D. in 1988 from the University of G?ttingen, Germany, where he remained until 1989, working in the area of field ion microscopy. He then joined the applied physical metallurgy group at GKSS, where he remained until 1993, before transferring to the group headed by Fritz Appel. Dr. Oehring received the Charles Hatchett Award in 2002 from the Institute of Materials, London, and has authored or co-authored over 100 papers as well as five patents.

INTRODUCTION CONSTITUTION Phase equilibria in the Ti-Al system Stable phases in multi-component alloys Important ternary phase diagrams PHYSICAL PROPERTIES Elastic and thermo-physical properties Point defects Diffusion PHASE TRANSFORMATIONS AND MICROSTRUCTURES Microstructure formation on solidification Directional solidification solid state phase transformations DEFORMATION BEHAVIOUR Kinematics of deformation Dislocation dynamics Hardening mechanisms Work hardening and work softening YIELD STRESS AND DUCTILITY Global effects of constitution and microstructure Brittle and ductile behaviour Statistical assessment CREEP General behaviour Effects of constitution and microstructure Mechanistic understanding General assessment FRACTURE Cleavage fracture Toughening mechanisms Fracture toughness Statistical assessment FATIGUE General behaviour Fatigue crack growth Effects of constituion and microstructure Effects of temperature OXIDATION RESISTANCE General properties (Al, Nb, Cr, TiAl-Ag) Halogen (Cl) effect Embrittlement Coatings ALLOY DESIGN Effect of aluminium content Influence of important alloying elements Process specific alloy development INGOT PRODUCTION AND CASTING Ingot production Cast components POWDER METALLURGY Elemental powder route Pre-allyed powder route Mechanical alloying WROUGHT PROCESSING Conversion of microstructure Primary ingot break-down Texture evolution Secondary processing Novel techniques JOINING Diffusion bonding Welding and soldering SURFACE HARDENING Shot peening Roller burnishing Residual stresses, microhardness and surface roughness Thermal stability of surface hardening APPLICATIONS AND COMPONENT ASSESSMENT