以Ti-Al-Ti3AlC2为反应体系,采用真空热压技术(1100℃×1 h)制备Ti2AlC/TiAl基复合材料.借助XRD、SEM等测试手段分析相组成以及微观结构,并测量其密度、维氏硬度、抗弯强度、抗压强度和断裂韧性等室温力学性能.结果表明,产物主要由TiAl、Ti2AlC和Ti3Al相组成.利用Ti3AlC2分解反应原位自生的Ti2 AlC增强相主要分布于基体晶界处,部分钉扎于晶内,且随着Ti2 AlC生成量的增大,团聚现象加剧.室温力学性能测试表明,Ti2 AlC/TiAl基复合材料的力学性能明显优于单相TiAl材料,当Ti3AlC2掺杂量为10 mass％时,综合性能较好,密度、硬度、抗弯强度、抗压强度和断裂韧性分别为3.97 g/cm3、4.82 GPa、488.61 MPa、1340 MPa和5.68 MPa·m1/2.断裂机制主要表现为沿晶断裂、穿晶断裂、裂纹偏转与桥联;颗粒相增韧、裂纹偏转与桥联以及层状增韧是主要的增韧方式.
Ti2AlC/TiAl composites were fabricated by vacuum hot pressing technique in the Ti-Al-Ti3AlC2 system at 1100 ℃ for 1 h.Phase constituent and microstructure of the composites were analyzed by XRD,OM and SEM.The room temperature mechanical properties such as the density,Vickers hardness,flexural strength,compressive strength and fracture toughness were measured.The results reveal that the products are mainly composed of Ti3Al,Ti2AlC and TiAl phases.In situ Ti2AlC reinforcements developed by decomposition reaction of Ti3 AlC2 are mainly distributed in the matrix grain boundaries,part of which pinning in the intracrystalline.With the increase of Ti2AlC content,the agglomeration phenomenon aggravates gradually.The room temperature mechanical properties tests indicate that the mechanical properties of the Ti2 AlC/TiAl composites are obviously superior to the single-phase TiAl material.The Ti2 AlC/TiAl composites with 10 mass％ Ti3AlC2 additive presents better comprehensive performance,and the density,Vickers hardness,flexural strength,compressive strength and fracture toughness are 3.97 g/cm3,4.82 GPa,488.61 MPa,1340 MPa and 5.68 MPa·m1/2,respectively.The fracture mechanism of the Ti2AlC/TiAl composites is mixed with many kinds of fracture mode,including intergranular fracture,transgranular fracture,crack deflection and crack bridging.The toughening ways mainly include particulates-toughening,crack deflection and bridging toughening,and laminated-toughening.
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