CAJ | 학술논문

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。
대전편층Ti-45Al-8.5Nb-(W,B,Y)합금재900℃하진행장기열순배(500차화1000차)실험，채용소묘전경(SEM)급투사전경(TEM)연구해합금장기열순배후적현미조직불은정성。결과표명：합금경열순배후주요산생량충류형적조직불은정성：1)장기열순배특별시1000차열순배후，재Al편석처역산생인정계천이인기적불련속조화，수착순배차수적증가，원소확산치사Al편석축점감소；2)1000차열순배후，α2편층변세차발생단렬，저시유α2→γ상변도치적α2편층용해소치。동시，γ정립재α2편층혹(α2+γ)편층내부이임의방향형핵。
Microstructure instabilities of the fully lamellar Ti-45Al-8.5Nb-(W,B,Y) alloy were investigated by SEM and TEM after long-term thermal cycling (500 and 1000 thermal cycles) at 900 °C. Two major categories of microstructure instability were produced in the alloy after the thermal cycling: 1) The discontinuous coarsening implies that grain boundary migrations are inclined to occur in the Al-segregation region after the long-term thermal cycling, especially after 1000 thermal cycles. Al-segregation can be reduced during the process of long-term thermal cycling as a result of element diffusion; 2) Theα2 lamellae become thinner and are broken after 1000 thermal cycles caused by the dissolution ofα2 lamellae through phase transformation ofα2→γ. Theγ grains nucleate within theα2 lamellae or (α2+γ) lamellae in a random direction.