(昆明理工大學(xué) 機(jī)電工程學(xué)院，昆明 650500)
摘 要: 采用納米壓痕儀對(duì)單晶鍺開展變載荷與定載荷雙劃痕實(shí)驗(yàn)。通過掃描電子顯微鏡(SEM)觀察了單晶鍺的劃痕形貌，并對(duì)劃痕深度、殘余深度、彈性回復(fù)率和摩擦因數(shù)等進(jìn)行分析；同時(shí)結(jié)合雙劃痕應(yīng)力場(chǎng)模型，揭示單晶鍺材料的去除機(jī)制和損傷行為。結(jié)果表明：變載荷刻劃時(shí)，材料會(huì)發(fā)生塑性變形、脆塑轉(zhuǎn)變和脆性斷裂；雙次刻劃過程中材料的脆塑轉(zhuǎn)變臨界深度減小，并更容易發(fā)生脆性去除。定載荷刻劃時(shí)，減小劃痕間距，材料的脆性斷裂程度增加，導(dǎo)致第二次刻劃時(shí)的劃痕深度和殘余深度曲線波動(dòng)增大，但是彈性回復(fù)率沒有發(fā)生改變。這些現(xiàn)象產(chǎn)生的主要原因是雙次刻劃會(huì)使劃痕附近材料的最大主應(yīng)力迅速增加，并且最大主應(yīng)力隨劃痕間距的減小而增大，這將導(dǎo)致裂紋擴(kuò)展并相互作用，最終造成材料發(fā)生嚴(yán)重的脆性斷裂。
關(guān)鍵字: 單晶鍺；雙次刻劃；應(yīng)力分析；去除機(jī)制；損傷行為
（Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500, China）
Abstract:The nano-indenter was used to conduct the double scratch experiment of single crystal germanium under variable and constant load. Scanning electron microscope (SEM) was used to observe the scratch morphology of single crystal germanium, and the scratch depth, residual depth, elastic recovery rate and friction coefficient were analyzed. Also, the removal mechanism and damage behavior of single crystal germanium materials were revealed combined with the double scratches stress field model. The results show that the material undergoes plastic deformation, ductile-brittle transition and brittle fracture under the variable load scratching, the critical depth of the ductile-brittle transition of the material under the double scratching reduces, and brittle removal is more likely to occur. The reduction of the scratch interval in constant load scratching will lead to an increase of brittle fracture of the material, which results in the increase of the fluctuation of scratch depth and residual depth curves during the second scratching, but the elastic recovery rate does not change. The reason for these phenomena is that double scratching will promote the maximum principal stress of the material near the scratch, and it increases as the scratch interval decreases, which will lead to the propagate and interaction of cracks, and eventually severe brittle fracture occurs.
Key words: single crystal germanium; double scratching; stress analysis; removal mechanism; damage behavior
