热处理对网状结构TiB_W/Ti60复合材料组织与性能的影响

使用大尺寸球形Ti60钛合金粉与细小TiB2粉,通过低能球磨与反应热压烧结,成功制备了增强相呈网状分布的TiB晶须增强Ti60合金基(TiB_W/Ti60)复合材料。对TiB_W/Ti60复合材料进行热处理,以改善其组织结构与力学性能。结果表明:随着固溶温度的升高,TiB_W/Ti60复合材料基体中初生α相(密排六方相)含量减少,相应地转变β组织(α′(马氏体)+残留β相(体心立方相))含量增加,TiB_W/Ti60复合材料的抗拉强度升高,塑性降低;经过1 100℃/1h固溶处理之后,TiB_W/Ti60复合材料的室温抗拉强度为1 470 MPa,延伸率为1.9%。经过时效处理后,转变β组织中的α′相分解成细小α+β相。经过1 100℃/1h固溶+600℃/8h时效处理后TiB_W/Ti60复合材料的硬度达到HV538,抗拉强度达到1 552 MPa,延伸率为1.5%,经过1 000℃/1h固溶+600℃/8h时效处理,其抗拉强度达到1 460 MPa,延伸率为2.2%。

Effects of heat treatment on microstructure and properties of TiBW/Ti60 composites with network microstructure

TiB whiskers reinforced Ti60 alloy matrix (TiB_W/Ti60) composites with the reinforcement distributing as network microstructure were successfully fabricated by using large spherical Ti60 alloy powders and fine TiB₂ powders and processes of low energy milling and reactive hot pressingsintering. Heat treatment was performed on TiB_W/Ti60 composites to improve their microstructure and mechanical properties. The results show that the fraction of the primary α phase (hexagonal closepacked phase)in TiB_W/Ti60 matrix decreases while that of the transformed β microstructure including α' (martensite) and residual β phase (body-centered cubic phase) increases with increasing solid solution temperatures. Therefore, the tensile strength of TiB_W/Ti60 composites increases while the ductility decreases with increasing solid solution temperatures. After solid solution by 1 100 ℃/1 h, the tensile strength of TiB_W/Ti60 composites is 1 470 MPa at room temperature along with an elongation of 1.9%. The α' phase in the transformed β microstructure translates into fine α+β phases after aging process. After solid solution by 1 100 ℃/1 h followed by aging at 600 ℃ for 8 h,the hardness of TiB_W/Ti60 composites reaches to HV538 and the tensile strength increases to 1 552 MPa along with an elongation of 1.5%.After solid solution by 1 000 ℃/1 h followed by aging at 600 ℃ for 8 h,the tensile strength increases to 1 460 MPa along with an elongation of 2.2%.