MOLECULAR DYNAMICS SIMULATION OF THERMALLY INDUCED MARTENSITIC TRANSFORMATIONS IN NiAl
NiAl热诱发马氏体相变的分子动力学模拟

In order to study the microscopic mechanism of martensitic nucleation and growth proeesses, molecular dynamics simulation of thermally induced martensitic transformation in stoichiometric NiAl alloy with B2 structure has been perfomied via the embedded atom method interatomic potential of NiAl alloy. The phase stability analysis of NiAl at 0 K and constant volume shows that an ordered bct structure with a ratio of lattice parameters of about 1.31 is stable while B2 structure is just metastable. The results of the simulations clearly show that only at some special sites caused by different vibrational properties of Ni and Al atoms the themially induced martensites can nucleate heterogeneously, and this has been further proved by simulations of two other systems with different initial configures. By calculating mean square displacements of Ni and Al atoms in NiAl, the reason of heterogeneous nucleation has been explained. Austenite transformed finally to fct L1_0 martensites, and during the martensite growth processes many transformation twins have formed in martensite.Correspondent: SHA Xianwei, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015