微观相场模拟弹性畸变能对L1_2相沉淀全过程的影响

Effect of elastic strain energy on L1_2 phase precipitation simulated by using microscopic phase-field method

基于微观相场法研究不同弹性畸变能对Ni_(75)Al_5V_(20)合金中L1_2相沉淀过程的影响。结果表明:虽然弹性畸变能不同,Ni_(75)Al_5V_(20)合金在温度为1250 K下沉淀时的显微组织演化过程都可大概分为4个阶段,但也有不同之处;在早期沉淀析出的L1_2相中,V原子的占位要远大于Al原子的占位,最终,随着弹性畸变能的增大,在L1_2相中Al原子的占位概率降低,V原子的占位概率增大。在生成化学计量比的L1_2有序相时,Al原子由L1_2相边界逐渐向其内部扩散,而V原子则与之相反,且各原子越靠近L1_2相的边界扩散速度越快,反之越慢。

The precipitation process of L12 phase in Ni75Al5V20 alloy was mainly simulated by using the microscopic phase-field kinetic mode. The results demonstrate that the process of microscopic morphology evolution can be divided into four stages for Ni75Al5V20 alloy at 1250 K on different elastic strain energy, but there also are some different points. The occupation probability of Al atom is greater than V atom in early precipitation of L12 phase when the elastic strain energy is existent. Eventually, with increasing the elastic strain energy, the occupation probability of Al atom reduces and the occupation probability of V atom increases in L12 phase. When stoichiometric L12 ordered phase generates, the Al atoms gradually diffuse from L12 phase boundaries to its internal, meanwhile, the V atoms gradually diffuse from L12 phase internal to its boundaries, and the atoms in L12 phase are more closer to boundary, their diffusion speed becomes more faster, conversely becomes more slowly.