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微尺度Ti-10V-2Fe-3Al單晶壓縮變形行為及其微觀機(jī)制
發(fā)布人：上海艾荔艾金屬材料有限公司www.bt990.com.cn
更新時(shí)間：2015-11-16
研究了尺寸為 0.3~2.0 μm 的 Ti-10V-2Fe-3Al(Ti1023)微柱沿[011]位向壓縮的變形行為及微觀機(jī)制.
微尺度Ti-10V-2Fe-3Al單晶壓縮變形行為及其微觀機(jī)制DEFORMATION BEHAVIOR AND THE MECHANISM OF MICRO-SCALE?Ti-10V-2Fe-3Al PILLARS IN COMPRESSION
研究了尺寸為 0.3~2.0 μm 的 Ti-10V-2Fe-3Al(Ti1023)微柱沿[011]位向壓縮的變形行為及微觀機(jī)制. 結(jié)果表明: Ti1023?微柱沿[011]位向壓縮的塑性變形階段應(yīng)力-應(yīng)變曲線光滑, 表現(xiàn)出持續(xù)加工硬化, 無(wú)應(yīng)變突發(fā)現(xiàn)象. 微柱屈服強(qiáng)度(σ0.2)隨試樣尺寸(d)的減小而增加, 其關(guān)系為: σ0.2∝d-0.18. 微柱塑性變形以{112}<111>滑移主導(dǎo), 應(yīng)變量超過(guò) 10%時(shí)產(chǎn)生應(yīng)力誘發(fā)馬氏體(α″), 應(yīng)力誘發(fā)馬氏體相變發(fā)生時(shí)的應(yīng)力(σcm)亦隨 d 的減小而增加, 其關(guān)系為: σcm∝d-0.28. 在均勻塑性變形階段, 應(yīng)變硬化指數(shù)(n)隨尺寸的減小而增加. 采用透射電鏡觀察了變形前后微觀組織形貌, 認(rèn)為 Ti1023 微柱沿[011]位向壓縮時(shí)表現(xiàn)出來(lái)的持續(xù)應(yīng)變硬化歸因于晶體中納米尺度 ω 相和 α″對(duì)位錯(cuò)滑移的阻礙作用.?
Ti and its alloys have potential application in micro-electromechanical systems (MEMS) for its?excellent mechanical properties. The strength of micro- and nano-scale Ti and its alloys has been proven ?significantly increased as the sample size decreased, which is known as the "size effect", when dislocation and?twinning are dominant plastic deformation modes. Martensitic transformation is an important plastic deformation?mode in the Ti alloys. However, there is a limited research on the martensitic transformation in small-scale.?Therefore, the study on mechanical behavior and deformation mechanisms of [011]-oriented Ti-10V-2Fe-3Al?(Ti1023) single crystal micropillars in a size range of 0.3~2.0 μm were investigated under uniaxial compression.?The results show that Ti1023 micropillars exhibit smooth stress-strain curves in the regime of plastic deformation?without a conventional strain burst phenomenon in the submicron pillars. It means continuous plastic strain?hardening. The relationship between the yield stress (σ0.2), the stress for stress-induced martensite phase (SIM)?transformation (σcm) and the sample size can be expressed in the forms of σ0.2∝d-0.18?and σcm∝d-0.28?, respectively.?Strain hardening exponent (n) increases with decreasing micropillar size. SEM examination together with?crystallography analysis show that {112}<111> slip predominates plastic deformation mode in the Ti1023?micropillars. Transmission electron microscopy (TEM) observation of microstructures in the deformed and?undeformed micropillars indicate that both nanoscale athermal ω particles and SIM phase α″?impede dislocation?movement, and prohibit the formation of tangled dislocations in a collective, avalanche-like way resulting in?strain bursts.
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