原位β-Zr相/Zr非晶基复合材料的干摩擦滑动磨损行为

Dry Sliding Wear Behavior of in-Situ β-Zr/Zr-Based Metallic Glass Matrix Composites

采用铜模喷铸法制备出直径为3 mm的原位β-Zr相/Zr非晶基复合材料,对其在干摩擦条件下的滑动磨损行为进行了研究。结果表明,与纯块状非晶合金相比,Zr基块状非晶复合材料的耐磨性能得到明显的改善。复合材料比纯块状非晶合金具有更低的摩擦系数和磨损速度,最低的磨损速度比纯非晶合金的减小48.1%。同时,包含一定体积分数β-Zr相的复合材料表面磨损比纯非晶合金的轻,只有一些浅的犁沟,其磨削小,显示出轻微的磨粒磨损特征,而纯非晶合金的磨损表面呈现出片状、分层、凸起及深的犁沟等特征,磨削大,为严重的磨粒磨损。复合材料低的磨损速度归因于铸态下析出的分布在非晶基体上的韧性β-Zr枝晶相的存在。该相具有较强的承载、塑性变形和加工硬化能力,通过减小界面处非晶基体的应力集中、释放应变能、限制剪切带和裂纹的萌生与扩展、使塑性变形更加均匀等途径提高耐磨性能。

In-situ β-Zr/Zr-based metallic glass matrix composites with 3 mm in diameter were fabricated by a conventional Cu-mold casting method and the wear behaviors under dry sliding condition of the composites were investigated. Results indicate that compared with the pure BMG, the composites exhibit a markedly improved wear resistance. The composites show lower friction coefficient and wear rate than the pure BMG. The lowest wear rate in these composites is 48.1% lower than that of the pure BMG. Meanwhile, the worn surface of the composite with a proper amount of β-Zr crystalline phase is less severe and there are shallow grooves with some fine wear debris on the worn surface, which exhibits the characteristic of mild abrasive, whereas that of the pure BMG is characterized by flakes, delamination, pile-up and deep grooves which show a severe abrasive wear mode. The wear resistance of the composites is improved since the β-Zr crystalline phase distributing in the amorphous matrix decreases strain accumulation, releases strain energy in the glassy matrix, restricts the expanding of shear bands and cracks, and makes plastic deformation homogeneous due to its effective load bearing, plastic deformation and work hardening ability.