(1. 中南大学 材料科学与工程学院，长沙 410083；2. 中南大学 教育部有色金属重点实验室，长沙 410083；
3. 佛山通宝精密合金股份有限公司，佛山 528000)
摘 要: 采用Gleeble−1500热模拟实验机对Ag-SnO2(10%，质量分数)复合材料进行高温压缩变形实验，分析该材料在变形温度为750~900 ℃、应变速率为0.01~1 s−1条件下的流变应力变化规律；采用透射电镜(TEM)观察Ag-SnO2(10%)复合材料热压缩变形后的显微组织。采用双曲正弦确定了该材料的变形激活能，建立了以Zener-Hollomon 参数描述的高温塑性变形本构模型，并验证了本构模型的准确性。结果表明：变形温度和应变速率均对流变应力有显著影响，流变应力随变形温度升高而减小，随应变速率的增加而增大。动态再结晶和孪晶共同作用是Ag-SnO2 复合材料热压缩变形的主要变形机制，随应变速率增加，孪晶数量增多，并形成了二次孪晶。
关键字: Ag-SnO2复合材料；热压缩变形；本构方程；显微组织
（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
