Abstract Based on the IN783 alloy of as-received state, post-serviced state and thermal-cycled state, this paper studied the Ni5Al3 phases appearing in the NiAl phase of IN783 alloy by optical microscope, transmission electron microscope. The type and formation process of Ni5Al3 phase were analyzed. The dynamic evolution of the crack initiation and propagation on as-received state and post-serviced state was in-situ observed by SEM, and the microcrack characteristic was studied. It is found that Ni5Al3 phase is present in the NiAl of IN783 alloy under post-serviced state and thermal-cycled state. There are two ways to form the Ni5Al3 phase in IN783 alloy. The Ni5Al3 phase formed during long-term service is due to element diffusion. The Ni5Al3 phase formed during the thermal cycle is mainly the crystal transformation of the M-NiAl phase to the Ni5Al3 phase. The crack of alloy in as-received state sprouts from the stress concentration of the matrix and expands in the matrix. There is no crack in the NiAl phase. In post-serviced state, the crack of the alloy starts from the NiAl phase, and then the cracks expand and connect, causing the material to break. After serving the alloy, the tensile strength increase, and the elongation decreases. After service, the hardness of NiAl phase decreases and the hardness of matrix increases, which makes the difference in mechanical properties between the two increase.

中文翻译：

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Ni5Al3相的形成及其对In783合金力学性能的影响

摘要 以IN783合金处于原样状态、服役后状态和热循环状态，通过光学显微镜、透射电子显微镜研究了IN783合金NiAl相中出现的Ni5Al3相。分析了Ni5Al3相的类型和形成过程。通过扫描电镜原位观察裂纹萌生和扩展在接受状态和使用后状态的动态演化，并研究了微裂纹特征。结果表明，在使用后状态和热循环状态下，IN783 合金的 NiAl 中存在 Ni5Al3 相。IN783合金中有两种形成Ni5Al3相的方法。在长期使用过程中形成的 Ni5Al3 相是由于元素扩散造成的。在热循环过程中形成的 Ni5Al3 相主要是 M-NiAl 相向 Ni5Al3 相的晶体转变。合金在原样状态下的裂纹从基体的应力集中萌生并在基体中扩展。NiAl相中没有裂纹。在后期服役状态下，合金的裂纹从NiAl相开始，然后裂纹扩展并连接，导致材料断裂。使用合金后，抗拉强度增加，延伸率降低。服役后，NiAl相硬度降低，基体硬度增加，使两者力学性能差异增大。在后期服役状态下，合金的裂纹从NiAl相开始，然后裂纹扩展并连接，导致材料断裂。使用合金后，抗拉强度增加，延伸率降低。服役后，NiAl相硬度降低，基体硬度增加，使两者力学性能差异增大。在后期服役状态下，合金的裂纹从NiAl相开始，然后裂纹扩展并连接，导致材料断裂。使用合金后，抗拉强度增加，延伸率降低。服役后，NiAl相硬度降低，基体硬度增加，使两者力学性能差异增大。