Open AccessPhase stability of transition metals and alloys
Author(s) -
R. S. Hixson,
D. Schiferl,
J. M. Wills,
Hill
Publication year - 1997
Language(s) - English
Resource type - Reports
DOI - 10.2172/481599
Subject(s) - transition metal , diamond , diamond anvil cell , alloy , materials science , phase transition , crystal (programming language) , stability (learning theory) , phase (matter) , thermodynamics , metallurgy , chemistry , high pressure , physics , computer science , biochemistry , programming language , catalysis , organic chemistry , machine learning
This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project was focused on resolving unexplained differences in calculated and measured phase transition pressures in transition metals. Part of the approach was to do new, higher accuracy calculations of transmission pressures for group 4B and group 6B metals. Theory indicates that the transition pressures for these baseline metals should change if alloyed with a d-electron donor metal, and calculations done using the Local Density Approximation (LDA) and the Virtual Crystal Approximation (VCA) indicate that this is true. Alloy systems were calculated for Ti, Zr and Hf based alloys with various solute concentrations. The second part of the program was to do new Diamond Anvil Cell (DAC) measurements to experimentally verify calculational results. Alloys were prepared for these systems with grain size suitable for Diamond Anvil Cell experiments. Experiments were done on pure Ti as well as Ti-V and Ti-Ta alloys. Measuring unambiguous transition pressures for these systems proved difficult, but a new technique developed yielded good results