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对全片层Ti-45Al-8.5Nb-(W,B,Y)合金在900℃下进行长期热循环(500次和1000次)实验,采用扫描电镜(SEM)及透射电镜(TEM)研究该合金长期热循环后的显微组织不稳定性。结果表明:合金经热循环后主要产生两种类型的组织不稳定性:1)长期热循环特别是1000次热循环后,在Al偏析处易产生因晶界迁移引起的不连续粗化,随着循环次数的增加,元素扩散致使Al偏析逐渐减少;2)1000次热循环后,α2片层变细且发生断裂,这是由α2→γ相变导致的α2片层溶解所致。同时,γ晶粒在α2片层或(α2+γ)片层内部以任意方向形核。
Long-term thermal cycling (500 times and 1000 times) experiments were carried out on the all-layer Ti-45Al-8.5Nb- (W, B, Y) alloy at 900 ℃. SEM and TEM Microstructure instability of the alloy after long-term thermal cycling. The results show that there are mainly two types of instability of the alloy after thermal cycling: 1) the long-term thermal cycling, especially after 1000 thermal cycles, is likely to cause discontinuous coarsening due to grain boundary migration at Al segregation With the increase of the number of cycles, the segregation of elements caused the segregation of Al to decrease gradually; 2) After 1000 thermal cycles, the α2 sheet became thinner and fractured, which was caused by the dissolution of α2 sheet caused by α2 → γ transformation. At the same time, the γ grains nucleate in either direction in the α2 sheet or in the (α2 + γ) sheet.