Statics and Dynamics of Alloy Phase Transformations

The study of phase transformations in substitutional alloys, including order disorder phenomena and structural transformations, plays a crucial role in understanding the physical and mechanical properties of materials, and in designing alloys with desired technologically important characteristics. Indeed, most of the physical properties, including equilibrium properties, transport, magnetic, vibrational as well as mechanical properties of alloys are often controlled by and are highly sensitive to the existence of ordered compounds and to the occurrence of structural transformations. Correspondingly, the alloy designer facing the task of processing new high-performance materials with properties that meet specific industrial applications must answer the following question: What is the crystalline structure and the atomic configuration that an alloy may exhibit at given temperature and concentration? Usually the answer is sought in the phase-diagram of a relevant system that is often determined experimentally and does not provide insight to the underlying mechanisms driving phase stability. Because of the rather tedious and highly risky nature of developing new materials through conventional metallurgical techniques, a great deal of effort has been expended in devising methods for understanding the mechanisms contrOlling phase transformations at the microscopic level. These efforts have been bolstered through the development of fully ab initio, accurate theoretical models, coupled with the advent of new experimental methods and of powerful supercomputer capabilities.

Proceedings of a NATO ASI held in Rhodes, Greece, June 21-July 3, 1992

Opening Remarks.- Experiment And Phenomenology:Invited Papers.- Experimental Determination Of Phase Diagrams.- Phenomenological Calculations Of Phase-Equilibria: The Calphad Approach.- Phase Stability Of A13X Alloys (X=Ti, Zr, Hf).- Diffuse Scattering Determination Of Short Range Order In Alloys.- To The Physics Of Quasicrystals.- Contributed Papers.- Thermodynamically Improbable Phase Diagram Features.- Formation Of Electron Phases In Binary s,p-Bonded Metal Alloys Under High Pressure.- In-Situ Diffuse Scattering Of Neutrons In Alloys And Application To Phase Diagram Determination.- Short-Range Order And Pair Interactions In Binary Nickel Alloys.- Verification Of Interatomic Interaction Energies By Means Of Monte-Carlo Simulation Of Short-Range Order And Internal Friction Spectra.- Separation Of Chemical And Topological Disorder In ASAXS Experiments.- Long-Range Ordering And Disordering In Cu-Pt.- Orientational Phase Transitions In Alloys.- X-ray Absorption Spectroscopy Investigations Of Atomic Reordering At ZnTe/CdSe Interfaces.- L12-D022 Competition In The Quasi-Binary (Pt,Rh)3V And (Pd,Rh)3V Alloys.- A TEM Survey On ?'/?' Composite Precipitates In An Al-2. 5%Li-0. 15%Zr Alloy.- The Effect Of Volume Fraction On ?' (Ni3Si) Precipitate Coarsening In Ni-Si Alloys.- Ion Damage Of Quasicrystalline Thin Films Of AI.83Mn. 17.- Electronic Approach To Stability And Transformations:Invited Papers.- The Energetics Of Ordered Intermetallic Alloys (Of The Transition Metals).- Quantum Theory Of Structure: Crystals And Quasicrystals, Melts And Glasses.- First Principles Theory Of Disordered Alloys And Alloy Phase Stability.- First-Principles Statistical Mechanics Of Semiconductor Alloys And Intermetallic Compounds.- Displacive Phase Transformations And Phonons.- ContributedPapers.- On Significance Of The Local Lattice Distortions, Bandstructure Variations And Charge Transfer Effects For Configurational Interactions In Substitutional Alloys.- Calculations Of Elastic Moduli From First Principles.- First Principles Studies Of Electronic Structure And Mechanical Properties Of Metallic Alloys.- Electronic Structure Of Planar Defects In Ordered And Disordered High Temperature Intermetallics.- Bonding Mechanisms And Interatomic Forces In Ni-Al Liquid Alloys.- Full-Potential CPA Theory Using Rectangular Matrices.- Fully Relativistic Multi-Site Interactions.- Statics of Alloy Transformations:Invited Papers.- Monte Carlo Simulations Of Alloy Phase Transformations.- The Cluster Variation Method And Some Applications.- Contributed Papers.- A Combined Monte Carlo and Cluster Variation Approach For Calculating Gibbs Energies And Chemical Potentials.- The Direct Monte Carlo Method For Calculating Alloy Phases.- Ground States And Ordering In Semiconducting (Chalcopyrite)-(Zinc Blende) Alloys.- LMTO/CVM Calculations Of Bcc-Based Phase Ordering In The System Fe-Be.- Ordering And Displacive Transformations In Ni-Al Alloys.- The Gibbs Energy Of Transition Metal Compounds.- AB Initio Computation Of The Fcc Pd-V Phase Diagram.- Evaluation Of Defect-Defect Pair Interactions In Non-Stoichiometric Oxides By CVM And Monte Carlo Calculations.- Phase Stability Of Fcc- And Hep-Based Intermetallics: The Ti-Al And Cd-Mg Systems.- Kinetics and Dynamics of Alloy Transformations:Invited Papers.- Morphology Transformations In Ordering And Phase Separating Materials.- Alloys Under External Forcing: Steady-States And Microstructural Evolutions.- Amorphous And Liquid Semiconducting Alloys Investigated By First Principles Molecular Dynamics.- Contributed Papers.- Continuous Displacement Of "Lattice" Atoms.- Spinodal Ordering Evidenced By PPM.- Kinetics Of Disorder ? Order Transformations: Thermodynamic Theory Versus Kinetic Rate Theory.- Kinetics Of An Inhomogeneous Ising Alloy.- Statics And Kinetics Of Phase Transformations In Bcc Fe-Cr.- Elastically Driven Phase Transitions Studied By A Continuous Monte Carlo Method.- On Theory Of Open Systems: Statistical Thermodynamics For The Alloy Under Irradiation Model.- Dynamics Of Radiation-Induced Amorphization In Ordered Intermetallic Compounds.- Dynamics Of Martensitic Transformations Examined In A Computer.- Tight-Binding Molecular Dynamics Of Semiconductor Clusters And Crystals.- A Parallel Molecular Dynamics Strategy For PVM.- Closing Remarks.- Invited Lecturers.- Participants.- Author Index.