循环热处理对定向凝固Ti-46Al-6Nb合金组织和力学性能的影响（英文）

发布时间：2018-03-04 03:21

本文选题：TiAl合金　切入点：循环热处理　出处：《Transactions of Nonferrous Metals Society of China》2015年06期 　论文类型：期刊论文

【摘要】：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1385.09MPa,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。
[Abstract]:Ti-46Al-6Nb (mole fraction) alloy was prepared by means of cold crucible directional solidification technology, and then the directional solidification ingot was treated by heat treatment. The heat treatment temperature is 1330 掳C and the heat treatment interval is in the 伪 phase single-phase region. The changes of microstructure and mechanical properties of the ingot before and after heat treatment are studied. Large columnar crystals are transformed into equiaxed crystals. With the increase of heat treatment cycles, the grain size decreases. This is due to recrystallization and the transition between large and small grains in small lamellar layers. Four cycles of heat treatment can effectively refine the grain size. The grain size was reduced from 1.33 mm to 0.59 mm, but the lamellar spacing was increased from 0.71 渭 m to 1.38 渭 m. The 尾 segregation phase between grains and laminates could be eliminated by prolonging the holding time and increasing the heat treatment cycles. The compressive strength parallel to the growth direction of columnar crystal is 1385.09 MPa, and the compressive strength perpendicular to the growth direction of columnar crystal is 1267.79 MPa, and the compressive strength of cast sample is 1180.64 MPa. After two cycles of heat treatment, the compressive strength of cast sample is increased to 1449.75 MPa, and the compressive strength of cast sample is increased to 1449.75 MPa after heat treatment. The compressive strength was increased to 1527.76 MPa after 4 times of heat treatment. The fracture mode of alloy specimen is quasi-cleavage fracture.
【作者单位】：哈尔滨工业大学材料科学与工程学院;
【基金】：Project(2011CB605504) supported by the National Basic Research Program of China Project(NCET-12-0153) supported by the Program of New Century Excellent Talents in University Project(51274076) supported by the National Natural Science of Foundation of China
【分类号】：TG166.5

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