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采用微观相场法模拟了Ni_(75)Al_5Cr_(20)合金的时效过程,研究了Cr和Al原子在无序fcc固溶体(001)和(002)面上序参数变化与相结构演化之间的关系.结果表明,合金时效序列为:无序基体→L1_0(M=1)预析出相→DO_(22)相.在时效的最初阶段,原子只在面内跃迁,发生面内原子有序化,形成L1_0(M=1)结构;此后,原子在面间跃迁,原子在(001)面上进一步有序化,在(002)面上无序化,L1_0(M=1)结构向DO_(22)结构转变.随温度降低,L1_0(M=1)预析出相孕育期和存在期缩短,从而导致DO_(22)相的孕育期缩短;L1_0(M=1)预析出相在低温下容易形成.
The microstructure of the Ni_ (75) Al_5Cr_ (20) alloy was simulated by the microscopic phase field method. The relationship between the change of the order parameters and the evolution of the phase structure of the (001) and (002) The results show that the phase sequence of the alloy is as follows: the disorder matrix → L1_0 (M = 1) pre-precipitation phase → DO_ (22) phase. At the initial stage of aging, (M = 1). The atoms then transition between the planes, and the atoms are further ordered on the (001) plane and disordered on the (002) plane. The structures of L1_0 (M = 1) 22), the incubation period of DO_ (22) phase was shortened with the decrease of temperature, and the pre-precipitation phase of L1_0 (M = 1) was easy at low temperature form.