Influence of modulated structures on ordering dynamics in CuAu

✍ Scribed by Bulbul Chakraborty; Ken Elder; Nigel Goldenfeld

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 752 KB
• Volume: 224
• Category: Article
• ISSN: 0378-4371
• DOI: 10.1016/0378-4371(95)00319-3

✦ Synopsis

Using a microscopic model, we have studied the evolution of microstructure in a model metallic alloy. The Hamiltonian was derived from the effective medium theory of cohesion in metals (EMT): an approximation scheme for integrating out the electronic degrees of freedom and constructing an effective classical Hamiltonian. The alloy chosen for this study was CuAu which exhibits a sequence of first-order phase transitions: disordered --~ modulated ~ ordered. To describe the dynamics of ordering, a free energy functional was constructed from the EMT Hamiltonian and used in a Langevin equation. This study demonstrates the feasibility of predicting microstructure in alloys starting from a description based on the electronic structure of alloys. The simulations exhibit interesting features in late-stage growth which are attributed to the presence of the modulated phase as a metastable phase in the ordered regime.