不同弹性畸变程度下Ni75Al14Mo11合金沉淀过程的多尺度模拟

基于微观相场模型和第一性原理方法模拟了Ni75Al14Mo11合金在不同弹性畸变能常数下的相变过程。当弹性畸变能从无到有时,沉淀相形貌由椭圆状变为块状,分布由不规则随机排列变为沿弹性"软"方向规则排列,具有一定方向性;弹性畸变能对短程DO22有序相的析出有抑制作用,并且对沉淀粗化过程的影响要大于对析出过程的影响;弹性畸变能对沉淀相的有序化及原子簇聚的影响并不是随着其增加而简单的起抑制或促进作用,而是与其取值范围有关。在相同的外界条件下,Ni、Al元素形成Ni3Al要比Ni、Mo元素形成Ni3Mo容易,导致Ni75Al14Mo11合金在1073 K时效下较易析出Ni3Al。

Multi-scale simulations for precipitation process of Ni75Al14Mo11 alloy with different elastic strain energy

The precipitation process of Ni75Al14Mo11 alloy in different elastic strain energy had been simulated by the microscopic phase-field model and the first principles.Simulation results show that the morphology of precipitates changes from elliptic shape to block shape when elastic strain energy is considered,and the irregular random arrangement of precipitates changes to regular arrangement along with the elastic soft direction.The elastic strain energy has inhibitory effect on the short range ordered phase DO22,and the effect on later coarsening process is greater than that on initial precipitation process.The influence of elastic strain energy on the ordering and clustering of precipitation is not simple inhibition or promotion with the increase of elastic energy,but related to the scope of elastic strain energy.In the same external canditions,the formation of Ni3Al from Ni,Al element is easier than the formation of Ni3Mo from Ni,Mo element,so Ni3Al is easier to precipitated while Ni75Al14Mo11 alloy is aged at 1073 K.