摘要
运用NiAl合金的镶嵌原子势,进行了B2结构NiAl中热诱发马氏体相变的分子动力学模拟,从而研究马氏体形核和长大的微观机理.首先进行了0K等体积条件下NiAl的相稳定性分析,发现0K时点阵参数c与a之比约为1.31的bct结构是稳定结构,B2结构只是一种亚稳结构.在热诱发马氏体相变的模拟过程中,由于NiAl中Ni原子和Al原子的振动性质存在着差异,造成了马氏体的不均匀形核.对另两种不同初始构型的系统进行的模拟进一步证实了不均匀形核的存在,并通过计算B2结构NiAl中Ni原子和Al原子的热运动均方位移解释了其原因.模拟中,B2结构奥氏体经热诱发马氏体相变转变为fctL1_0结构的马氏体.马氏体在长大过程中内部形成了若干转变孪晶.
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
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
1996年第7期685-694,共10页
Acta Metallurgica Sinica
关键词
马氏体
相变
分子动力学
模拟
镍铝合金
martensitic transformations, molecular dynamics simulation, embedded atom method, NiAl