关键词: 单晶高温合金, 持久性能, 微观组织, 晶体取向

Abstract: Ni₃Al-based single crystal superalloys with [001] and [111] orientations were prepared, and the stress rupture property of the alloys was tested at 980 ℃/186 MPa and 1040 ℃/135 MPa, respectively, and the effect of crystal orientation on the stress rupture property of the alloys was analyzed. The results show that after solution and aging treatment, the γ′ phase in the [001] oriented specimen is cubic, the γ′ phase on the section in the [111] oriented specimen is triangular, and the volume fraction of the γ′ phase in the two specimens is about 70%. Under the conditions of 980 ℃/186 MPa and 1040 ℃/135 MPa, the [111] oriented specimens show higher stress rupture lifetimes, which are 510.81 h and 285.36 h, 12.6 and 17.6 times higher than that of the [001] oriented specimens. Under high temperature and low stress conditions, the fracture modes of both oriented alloys are microvoid coalescence fracture, with P-type rafting of the γ′ phase occurring in the stress rupture of the [001] oriented specimen, and no specific rafting direction for the [111] oriented specimen. The distinctive γ/γ′ rafting structure in the [111] oriented specimen, the dense interfacial dislocation networks, and low Schmid factor that make it difficult to activate the slip systems, thus improving the stress rupture deformation resistance.

Key words: single crystal superalloy, stress rupture property, microstructure, crystal orientation