热处理对铸造TiB+La_2O_3增强钛基复合材料微观组织和拉伸性能的影响

Effect of heat treatment on microstructure and tensile properties of in situ synthesized( TiB + La_2O_3) /Ti composite casting

利用Ti与La B6之间的化学反应经普通的熔铸工艺原位合成了Ti B和La2O3增强的钛基复合材料,而后复合材料浇铸成20 mm的棒材。研究了α+β和β热处理对复合材料的组织和拉伸性能的影响,利用光学显微镜和扫描电镜研究热处理后材料的微观组织和拉伸试样断面上增强体的增强机制。结果表明,α+β热处理后复合材料为α+β片层与少量近等轴α的混合组织,β热处理后复合材料为网篮组织。β热处理后复合材料的室温抗拉强度为1190 MPa,比α+β热处理的提高了31 MPa;β热处理后复合材料在600℃的抗拉强度为793 MPa,比α+β热处理的提高了48 MPa。复合材料在室温和600℃的断裂机制为Ti B纤维的承载断裂,在650℃和700℃的断裂机制为Ti B纤维的承载断裂和少量脱粘。

In situ synthesized（ Ti B ＋ La2O3） /Ti composite has been fabricated by common casting utilizing the reaction between titanium and La B6.Then,the metal was cast into bars with diameter of 20 mm.The effects of α ＋ β and β heat treatment on microstructure and tensile properties of the as-cast composite were studied.The microstructure and fracture morphologies of the specimens after heat treatment were examined by OM and SEM.The results show that matrix microstructure of the composite via α ＋ β heat treatment combines α ＋ βlamellar structure and a little near equiaxed α.Basket weave structure is obtained after β heat treatment.The tensile strength of titanium matrix composite after β heat treatment at room temperature is 1190 MPa,with an increase of 31 MPa than composite via α ＋ β heat treatment.The tensile strength of titanium matrix composite after β heat treatment at 600 ℃ is 793 MPa,with an increase of 48 MPa than composite via α ＋ β heat treatment.The damage mechanism of the composite is that Ti B fiber fractures in load bearing at room temperature and 600 ℃.The damage mechanism of the composite is that Ti B fiber fractures in load bearing and Ti B debonding at 650 ℃ and 700 ℃.