冷却速率对Ti_3Al合金组织和拉伸性能的影响  

EFFECT OF COOLING RATE ON MICROSTRUCTURE AND TENSILE PROPERTIES IN Ti_3Al ALLOY

作　　者：王震[1] 曹磊[1,2] 刘仁慈[1] 刘冬[1] 崔玉友[1] 杨锐[1] 

机构地区：[1]中国科学院金属研究所,沈阳110016 [2]东北大学材料与冶金学院,沈阳110819

出　　处：《金属学报》2013年第11期1487-1492,共6页Acta Metallurgica Sinica

摘　　要：对两相区锻造的Ti_3Al合金棒材分别在1020和1150℃保温30 min,以10,1.5和0.3℃/s速度冷至室温,研究了冷速对Ti_3Al合金组织和拉伸性能的影响.结果表明,在1020℃固溶,冷速为10℃/s时,合金主要由B2相和α_2相组成;降低冷速,基体中均匀析出针状α_2/O相;冷速为0.3℃/s,等轴α_2/O相体积分数增加,针状α_2/O相粗化.随着冷速下降,合金的室温强度先升高后下降,塑性先降低后提高;600℃拉伸强度逐渐下降,塑性提高.在1150℃固溶,快速冷却时,合金主要由B2相构成,晶粒尺寸约为440μm;降低冷速,晶内均匀析出α_2/O相,呈网篮状;冷速0.3℃/s时,基体中析出的α_2/O相片层呈集束状.随着冷速下降,室温强度下降,而塑性先升高后降低;600℃拉伸强度先升高后降低,而塑性逐渐上升.结合组织分析表明,Ti_3Al合金的强度取决于晶界和α_2/O片层的尺寸,塑性受B2相体积分数以及α_2/O相的分布及体积分数影响.冷速为1.5℃/s时,Ti_3Al合金具有良好的综合力学性能.The microstructure and tensile properties in Ti3Al alloy rod by forging in the （B2＋α2） region after heating at 1020 and 1150℃ for 30 min and cooling to room temperature at the cooling rates of 10, 1.5 and 0.3℃/s were investigated. The results showed that Ti3Al alloy structure was mainly composed of B2 phase and α2 phase at the cooling rate of 10℃/s after heating at 1020℃. With the decrease of cooling rate, the acicular α2/O phase homogeneously precipitated in the matrix on slow cooling. The volume fraction of equiaxed α2/O phase increased and the acicular α2/O phase was coarsed under the cooling rate of 0.3℃/s. For room temperature tensile tests, the data indicated that the strength initially increased and then decreased and the ductility firstly decreased and then increased with reducing cooling rate. During the 600℃ tensile tests, the strength decreased monotonically and ductility rose as reducing cooling rate. When solid solution temperature was 1150℃, Ti3Al alloy was mainly composed of B2 phase and the size of grain was 440 $／mu$m by fast cooling. Basketweave structure was obtained in the grain at the cooling rate of 1.5℃/s. The α2/O phase colony precipitated in the B2 phase with further reducing the cooling rate. With the decrease of cooling rate, the strength decreased gradually and ductility initially increased and then decreased at the room temperature, the 600℃ tensile strength firstly went up and then down and ductility increased. Through microstructure analysis, strength in Ti3Al alloy is controlled by boundary and the size of α2/O phase, and ductility is decided by the number of B2 phase and α2/O phase and the shape of α2/O phase. The good comprehensive properties were obtained at the cooling rate of 1.5℃/s.

关 键 词：TI3AL合金 冷却速率 显微组织 拉伸性能 

分 类 号：TG146.2[一般工业技术—材料科学与工程]