热挤压与热处理对网状TiBw/TC18复合材料组织及性能的影响

Effect of Hot Extrusion and Heat Treatment on the Microstructure and Tensile Properties of Network Structured Ti Bw/TC18 Composites

对不同增强相含量的TiBw/TC18进行了热挤压与热处理,利用OM、SEM、TEM及电子万能试验机研究了热挤压与热处理对复合材料的组织与拉伸性能的影响。结果表明,通过β单相区挤压变形,Ti Bw/TC18的β晶粒由70μm减小到40μm左右,TiBw呈定向排列。挤压态TiBw/TC18通过三重退火与固溶时效处理后,基体组织变为不同尺寸的α相分布在β相基底上,这种多尺度的组织使TiBw/TC18获得了优异的综合性能。力学性能测试结果表明,挤压处理可明显提升烧结态TiBw/TC18复合材料的延伸率,但强度下降17%。经三重退火处理后,2.0%TiBw/TC18 (体积分数)的抗拉强度和延伸率分别达到1200 MPa和21.7%,较烧结态分别提高了5.5%和189%。而采用固溶时效处理后,2.0%TiBw/TC18复合材料的抗拉强度和延伸率分别为1389 MPa和9.9%,较烧结态分别提高了22.2%和32%。2种热处理制度均实现了复合材料强度和塑性的协同提升。网状结构TiBw/TC18通过挤压与不同制度的热处理可以调控其性能,以满足不同服役条件的使用需求。

To improve the comprehensive performance of Ti matrix composites for defense applications such as aviation and aerospace,as-sintered Ti Bw/TC18 composites with different reinforcement contents were hot extruded and heat-treated.The composites were characterized and analyzed by OM,SEM,and TEM.The mechanical properties of the composites were measured using an electronic universal testing machine.By extruding in the β single-phase region,the β grain size of TiBw/TC18 was reduced from 70 μm to about 40 μm.After the subsequent triple-annealing or solution aging heat treatment,α phase with different sizes was precipitated and distributed in the β phase.The elongation of the asextruded composites significantly showed improvement,but the strength decreased by about 17%.After applying the triple-annealing heat treatment,the tensile strength and elongation of 2.0%TiBw/TC18(volume fraction) reached 1200 MPa and 21.7%,which are higher by 5.5% and 189%,respectively,than those in the sintered state.Moreover,after applying the solution aging heat treatment,the as-extruded2.0%TiBw/TC18 exhibited tensile strength and elongation of 1389 MPa and 9.9%,which are higher by22.2% and 32%,respectively,than those exhibited by as-sintered 2.0%TiBw/TC18.Consequently,the hot extrusion can effectively reduce the grain size of as-sintered TiBw/TC18,and the tensile properties of the extruded TiBw/TC18 can be modified to meet the requirements of different service conditions through different subsequent heat treatments.