非晶55Mg35Ni10Si块体的制备及力学性能

利用机械合金化方法制备55Mg35Ni10Si三元非晶合金粉末,以该非晶粉末为基础材料,采用真空热压法制备55Mg35Ni10Si非晶块体,利用显微硬度测试等手段考察其力学性能。DSC和XRD分析表明,粉体和块体材料中均出现一个明显的放热峰,结合高分辨电子显微镜观察证明,真空热压后块体材料总体上仍以非晶相为主并含少量纳米晶,而块体材料的晶化峰温度要略低于非晶粉末。力学性能测试表明,块体材料的显微硬度为7 834-8 048 MPa,且随载荷的增加而下降,与传统晶态材料的硬度-载荷依赖关系相似。块体材料的断口呈山峦状,没有明显塑性形变的特征,断裂裂纹扩展沿压痕对角线呈放射状。

Fabrication and mechanical properties of bulk amorphous 55Mg35Ni10Si alloy

Powders of 55Mg35Ni10Si amorphous alloy were prepared by mechanical alloying method. Using the mechanically alloyed powders as row material, bull amorphous 55Mg35Ni10Si alloy was prepared by vacuum thermal consolidation. The mechanical properties of bull material were characterized by micro-hardness. It is found that exothermic peaks appear at the DSC curves of both the powder and bulk material. In combination with the HRTEM examination, it is demonstrated that the bull material mainly consists of amorphous phase together with some nano-crystals. In addition, the crystallization peak temperature of bulk material shifts toward low temperature compared with that of the corresponding powders. The micro-hardness of bull material varies between 7 834 MPa and 8 048 MPa and decreases with increasing applied load, being in agreement with that of the normal crystalline materials. The fracture surface shows a mountain-like morphology without obvious plastic deformation features and the cracks propagate along the diagonal lines of the indentation.