Abstract The microstructures and mechanical properties of 60NiTi alloys after solution treated at 980 °C, 1005 °C, 1030 °C and 1055 °C for 2 h, 4 h, 8 h were studied. The results showed that there was undissolved Ni3Ti phase in the specimens after heat treated at 980 °C and 1005 °C for 8 h, and the specimens consisted of Ni3Ti, B2 NiTi and Ni4Ti3 phase. The volume fraction of the Ni4Ti3 phase was about 36% and 46% respectively. After heated at 1030 °C and 1055 °C for 8 h, specimens consisted of B2 NiTi and Ni4Ti3 phase, and the Ni3Ti phase was totally dissolved into the matrix. As a result, the volume fraction of Ni4Ti3 phase increased to 69% and 64%. Higher density of the Ni4Ti3 phase contributed to the higher hardness and higher ultimate compressive strength. The fracture modes of samples after solution treated were mainly quasi-cleavage fracture. The undissolved Ni3Ti phase improved the fracture toughness of the binary alloy. Crack propagation path in Ni3Ti rich area was featured by a zigzag mode, which indicated that Ni3Ti phase displayed positive effect on fracture toughness. The toughening mechanism of 60NiTi with Ni3Ti phase is emphasized.

中文翻译：

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固溶热处理对60NiTi显微组织演变和力学行为的影响

摘要 研究了60NiTi合金在980℃、1005℃、1030℃和1055℃下固溶处理2h、4h、8h后的组织和力学性能。结果表明，在980℃和1005℃热处理8h后，试样中存在未溶解的Ni3Ti相，试样由Ni3Ti、B2NiTi和Ni4Ti3相组成。Ni4Ti3 相的体积分数分别约为 36% 和 46%。在 1030 ℃和 1055 ℃加热 8 h 后，试样由 B2 NiTi 和 Ni4Ti3 相组成，Ni3Ti 相完全溶解在基体中。结果，Ni4Ti3 相的体积分数增加到 69% 和 64%。Ni4Ti3 相的更高密度有助于更高的硬度和更高的极限抗压强度。固溶处理后试样的断裂方式以准解理断裂为主。未溶解的 Ni3Ti 相提高了二元合金的断裂韧性。Ni3Ti富集区裂纹扩展路径呈锯齿状，表明Ni3Ti相对断裂韧性有积极影响。强调了含 Ni3Ti 相的 60NiTi 的增韧机制。