Alloy phase diagrams are used by metallurgists, materials engineers, and materials scientists to develop new alloys for specific applications; fabricate these alloys into useful configurations; design and control heat treatment procedures for alloys that will produce the required mechanical, physical, and chemical properties; and solve problems that arise with the performance of alloys in commercial applications.

ASM International has a proud history in the field of phase diagrams, including the ASM/NIST Data Program for Alloy Phase Diagrams and the resultant Phase Diagram Monograph Series; the Alloy Phase Diagram International Commission (APDIC) formed in partnership with other programs throughout the world; the online ASM Alloy Phase Diagram Database; the Journal of Phase Equilibria and Diffusion; and reference books including Binary Alloy Phase Diagrams, Second Edition; Handbook of Ternary Alloy Phase Diagrams; Desk Handbook: Phase Diagrams for Binary Alloys; and Phase Diagrams of Dilute Binary Alloys.

In the last 20 years, the phase diagram community has benefitted from marked improvements in experimental techniques, allowing for more accurate results. Even more importantly, computer modeling calculation methods have become more refined and reliable, to the point of augmenting or even replacing experimental results. Phase equilibria results that previously could not be determined practically, now can be found by these new calculation methods. This necessitated revisions of many previously accepted phase diagrams, prompting ASM to revise ASM Handbook, Volume 3, Alloy Phase Diagrams, first published in 1992.

Hiroaki Okamoto, Ph.D., Professor Emeritus of Asahi University, an editor of ASM International's Journal of Phase Equilibria and Diffusion and senior technical editor of the original Volume 3, led the effort to revise the Volume. Dr. Okamoto knew the 1992 edition could be improved upon significantly, because of his experience in recent years reviewing the literature and finding incorrectly drawn binary diagrams, based on thermodynamic arguments. Dr. Okamoto's decades of experience and his recent role as editor of ASM International's Desk Handbook: Phase Diagrams for Binary Alloys, Second Edition, prepared him for the laborious redrawing and updating of numerous binary and ternary diagrams for this new Volume. Dr. Okamoto, who has been involved with ASM publications for more than 35 years, was the perfect choice for the job, as he has studied, evaluated, and edited more diagrams than any other person alive today.

Mark E. Schlesinger, P.E., Professor of Metallurgical Engineering at Missouri University of Science and Technology, and an associate editor of the Journal of Phase Equilibria and Diffusion, contributed his expertise to this Volume by first selecting and then reviewing for accuracy and completeness the ternary diagrams. Erik M. Mueller, Ph.D., P.E., Materials Research Engineer at the National Transportation Safety Board, and a member of the ASM Handbook Committee, provided critical technical input in his review of the numerous introductory articles that now comprise Section 1 of the new edition.

Dr. Okamoto, or Hiro, as he is known to his colleagues, called upon two phase diagram subject matter experts—Dr. Hiroshi Ohtani, Professor at the Institute of Multidisciplinary Research for Advanced Materials at Tohoku University and Vice Chairman of the Japanese Committee for Alloy Phase Diagrams; and Dr. Seiji Miura, Professor in the Division of Materials Science and Engineering at Hokkaido University and Member of the Japanese Committee for Alloy Phase Diagrams—to review the binary diagrams. This Volume is enriched by their expertise.

ASM Handbook, Volume 3, Alloy Phase Diagrams, was prepared under the direction of the ASM Handbook Committee and the ASM Alloy Phase Diagram Committee, both of which confirmed the Volume should use the weight percent scale, rather than the atomic percent scale, to express alloy composition because most engineers still use weight percent to represent component concentration. This decision demonstrates ASM's continuing commitment to its members and its responsiveness to the phase equilibria community.

ASM International is grateful for the hard work and dedication of its Volume Editors, Hiroaki Okamoto, Mark E. Schlesinger, and Erik M. Mueller, and peer reviewers, Hiroshi Ohtani and Seiji Miura, who gave of their extensive expertise and time to make the Volume 3 revision a noteworthy addition to the ASM Handbook series.