CAJ | 학술논문

利用冷坩埚定向凝固技术制备Ti?46Al?6Nb (摩尔分数，%)合金，然后对定向凝固铸锭进行热处理，热处理温度为1330°C，热处理区间在α相单相区。研究热处理前后铸锭显微组织和力学性能的变化。结果表明：铸锭经过热处理后，大的柱状晶转变为等轴晶。随着热处理循环次数的增加，晶粒尺寸减小，这是由于发生了再结晶和小片层的大晶粒与大片层的小晶粒之间的转变。四次循环热处理能够有效地细化晶粒尺寸，使晶粒尺寸从1.33 mm降低到0.59 mm，然而片层间距从0.71μm增加到1.38μm。延长保温时间和增加热处理循环次数能够消除晶粒间和片层间的β偏析相。压缩实验结果表明，对定向凝固铸锭，平行于柱状晶生长方向的压缩强度为1385.09 MPa，垂直于柱状晶生长方向的压缩强度为1267.79 MPa；铸造试样的压缩强度为1180.64 MPa，经热处理循环两次后压缩强度提高到1449.75 MPa，热处理循环4次后压缩强度提高到1527.76 MPa。循环热处理后，合金试样的断裂方式为准解理断裂。
이용랭감과정향응고기술제비Ti?46Al?6Nb (마이분수，%)합금，연후대정향응고주정진행열처리，열처리온도위1330°C，열처리구간재α상단상구。연구열처리전후주정현미조직화역학성능적변화。결과표명：주정경과열처리후，대적주상정전변위등축정。수착열처리순배차수적증가，정립척촌감소，저시유우발생료재결정화소편층적대정립여대편층적소정립지간적전변。사차순배열처리능구유효지세화정립척촌，사정립척촌종1.33 mm강저도0.59 mm，연이편층간거종0.71μm증가도1.38μm。연장보온시간화증가열처리순배차수능구소제정립간화편층간적β편석상。압축실험결과표명，대정향응고주정，평행우주상정생장방향적압축강도위1385.09 MPa，수직우주상정생장방향적압축강도위1267.79 MPa；주조시양적압축강도위1180.64 MPa，경열처리순배량차후압축강도제고도1449.75 MPa，열처리순배4차후압축강도제고도1527.76 MPa。순배열처리후，합금시양적단렬방식위준해리단렬。
The Ti?46Al?6Nb (mole fraction, %) ingots that were directionally solidified by cold crucible were cyclic heat treated at 1330 °C in theα phase region. The microstructures and mechanical properties of the ingots before and after heat treatment were investigated. The results show that the large columnar grains are changed into equiaxed grains after heat treatment. The grain size decreases with increasing the cyclic times, which is caused by the recrystallization and the transition from the large grain of small lamellae to the small grain of large lamellae. Four times of cyclic heat treatment refines the grain size from 1.33 mm to 0.59 mm, nevertheless the lamellar spacing increases from 0.71 μm to 1.38 μm. Extending the holding time and increasing the cyclic times of heat treatment eliminate theβ-segregation at the grain boundary and the interlamellar. The compression testing shows that the compressive strength of the directionally solidified ingot in the parallel and perpendicular directions are 1385.09 MPa and 1267.79 MPa, respectively, which are improved to 1449.75 MPa and 1527.76 MPa after two and four times of cyclic heat treatment, respectively, while that is 1180.64 MPa for the as-cast sample. The fracture mode of the sample after cyclic heat treatment is quasi-cleavage fracture.