原位自生颗粒增强BH135活塞材料的组织与高温力学性能研究

将KFB4、K2TiF6混合盐加入到BH135合金熔体中通过原位合成反应制备了TiB2颗粒增强BH135铝基复合材料。光学显微镜、扫描电子显微镜对材料的微观组织结构分析表明TiB2颗粒尺寸在200nm左右,其均匀分布与晶界及α-Al初晶内。高温拉伸试验表明复合材料在300？C的抗拉强度较基体合金提高了30%,其值为160MPa,且复合材料的断裂方式为韧性断裂。复合材料高温性能提高的机理在于原位自生纳米级颗粒的加入,提升了复合材料晶界及α-Al初晶的高温强度。

Microstructure and high temperature mechanical properties of in situ TiB2/BH135 composite

In situ TiB2 / BH135 composite was synthesized through adding mixed salts（ KFB4 and KTiF6） into molten 7 BH135 alloy. Optical microscopy and Scan Electronic microscopy（ SEM） were adapted to analysis microstructure of the composite. The size of in- situ TiB2 particulates was about200 nm which were mainly distributed along the grain boundary region and some were distributed within α- Al during solidification. The tensile strength of composite at 300？ C was much higher than BH135 alloy because of the occurrence of TiB2,its value is about 160 MPa. The fracture appears to have a ductile character. The strengthening mechanisms mainly involve dislocation effect,dispersion effect and refining effect。