恒定大载荷划痕试验下紫铜的三维形貌及划痕硬度分析

Analysis of 3D Morphology and Scratch Hardness of Copper under Large Constant Load

采用圆锥形压头对紫铜进行划痕试验,并通过三维表面形貌仪获取划痕的三维形貌,研究正压力的变化对划痕沟槽所产生的影响.结果表明:正压力的增大,使得划痕宽度和深度均线性增加,当正压力较大时,位错墙的形成使划痕深度出现周期性的波动,同时压头划刻过程伴有划痕两侧和前端的材料堆积现象,前端堆积高度和厚度、两侧堆积高度和宽度随着正压力的增加而线性增大.通过"切削与塑性比"说明了压头对紫铜的刻划存在微犁耕和微切削两种变形机制,并且微切削机制在划刻过程中占主导地位.磨损率随着载荷增加而线性增大,但划痕硬度不随载荷的变化而改变,约为0.77 GPa.

Scratch tests were conducted on copper with a conical indenter. 3D morphologies of the scratches were obtained by a 3D Surface Profilometer,and the influence of normal force on the scratch groove was studied. The results show that width and depth of the scratches increase linearly with the increase in the applied normal force. When the normal force is high,the periodic fluctuation of scratch depth appears due to the formation of the dislocation walls. At the same time,the scratching process is accompanied by pile-up on both sides and in front of the indenter. It is found that height and thickness of the pile-up at the end of the scratch and the height and width of the pile-up on both sides of the scratch increase linearly with the increase of the applied normal load. The ratio of cutting to plasticity shows two deformation mechanisms: micro-ploughing and micro-cutting,and micro cutting mechanism plays the dominant role in the scratching process,resulting in a linear increase of wear rate with the increase of normal load. The scratch hardness does not change with the variation of normal load,and can be regarded to be a constant about 0.77 GPa.