(1. 中南大學(xué) 材料科學(xué)與工程學(xué)院，長(zhǎng)沙 410083；2. 中南大學(xué) 教育部有色金屬重點(diǎn)實(shí)驗(yàn)室，長(zhǎng)沙 410083；
3. 佛山通寶精密合金股份有限公司，佛山 528000)
摘 要: 采用Gleeble−1500熱模擬實(shí)驗(yàn)機(jī)對(duì)Ag-SnO2(10%，質(zhì)量分?jǐn)?shù))復(fù)合材料進(jìn)行高溫壓縮變形實(shí)驗(yàn)，分析該材料在變形溫度為750~900 ℃、應(yīng)變速率為0.01~1 s−1條件下的流變應(yīng)力變化規(guī)律；采用透射電鏡(TEM)觀察Ag-SnO2(10%)復(fù)合材料熱壓縮變形后的顯微組織。采用雙曲正弦確定了該材料的變形激活能，建立了以Zener-Hollomon 參數(shù)描述的高溫塑性變形本構(gòu)模型，并驗(yàn)證了本構(gòu)模型的準(zhǔn)確性。結(jié)果表明：變形溫度和應(yīng)變速率均對(duì)流變應(yīng)力有顯著影響，流變應(yīng)力隨變形溫度升高而減小，隨應(yīng)變速率的增加而增大。動(dòng)態(tài)再結(jié)晶和孿晶共同作用是Ag-SnO2 復(fù)合材料熱壓縮變形的主要變形機(jī)制，隨應(yīng)變速率增加，孿晶數(shù)量增多，并形成了二次孿晶。
關(guān)鍵字: Ag-SnO2復(fù)合材料；熱壓縮變形；本構(gòu)方程；顯微組織
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory for Nonferrous Metal, Education Ministry, Central South University, Changsha 410083, China;
3. Foshan Electrical Precision Alloy Co. Ltd., Foshan 528000, China）
Abstract:The flow stress behaviors of Ag-SnO2 (10%, mass fraction) composite material prepared by powder metallurgical method were investigated on Gleeble−1500 machine at temperatures of 750−900 ℃ and strain rates of 0.01−1 s−1. The microstructures of Ag-SnO2 (10%) composite materials after hot compression deformation were characterized by transmission electron microscopy (TEM). The deformation activation energy was calculated using the hyperbolic-sine mathematics model, and the flow stress constitutive equation of Ag-SnO2 composite during hot compression was represented by Zener-Hollomon parameter. The results indicate that the flow stress depends on the strain rate and deformation temperature. The flow stress increases with the strain rate increasing and decreases with deformation temperature increasing. The flow stress of Ag-SnO2 composite predicted by the proposed models well agrees with experimental results. The combined action of dynamic recrystallization and twins crystals is the main deformation mechanism in the hot compression of Ag-SnO2 composite. The quantity of twin crystals increases with the strain rates increasing and also the secondary twins are observed.
Key words: Ag-SnO2 composite; hot compression; constitutive equation; microstructures
