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基于微观相场模型,研究了Ni64Al21V15合金在1150K时效过程中相结构演化。结合微观组织演化图像和各个格点上原子占位几率的演化,分析了DO22结构向L10(M=1)结构转变机制。合金沉淀中期,在相界处析出L10(M=1)结构。研究发现,L10(M=1)结构形成可分为3类:在DO22与L12相界处形核,沿[001]方向排列,向DO22相扩张;在DO22结构90°有序畴界处形核,沿[001]方向排列,向DO22扩张;在2个[100]向排列的DO22结构交界处形核,沿[100]方向排列,向DO22结构扩张。DO22相中,V主要占据β位,Ni主要占据α2和α3位,Al主要占据α1位;随后,V向α2位跃迁,在(002)面富聚且发生有序化,逐渐占据β和α2位,Ni原子发生面间跃迁,由α2位跃迁至α1位,逐渐占据α1和α3位,Al原子向相外扩散。DO22结构最终转变为高度有序的L10(M=1)结构。
Based on the microscopic phase field model, the phase structure evolution of Ni64Al21V15 alloy at 1150K aging was studied. Based on the evolutionary images of microstructures and the evolution of atomic occupancy at each lattice point, the mechanism of the transition from DO22 structure to L10 (M = 1) structure was analyzed. In the mid-stage of precipitation, the L10 (M = 1) structure is precipitated at the phase boundary. It is found that the formation of L10 (M = 1) can be divided into three types: nucleation at the interface between DO22 and L12, alignment along [001], and expansion toward DO22; The nuclei are arranged in the direction of [001] and expanded toward DO22. The nuclei are nucleated at the alignment of DO22 structures arranged in [100] direction and arranged in the direction of [100] to expand to DO22 structure. In the DO22 phase, V mainly occupies the β site, Ni mainly occupies the α2 and α3 sites, and Al mainly occupies the α1 site. Subsequently, V changes to the α2 site and is enriched and ordered at the (002) plane, gradually occupying β and α2 Ni atom undergoes an interfacial transition and transitions from the α2 position to the α1 position, gradually occupying the α1 and α3 positions, and the Al atoms diffuse outwardly. The DO22 structure eventually transforms to a highly ordered L10 (M = 1) structure.