Compressive response and microstructural evolution of in-situ TiB_(2)particle-reinforced 7075 aluminum matrix composite  

原位TiB_(2)颗粒增强7075铝基复合材料的热压缩变形行为和显微组织演变

作　　者：Han WANG Hai-ming ZHANG Zhen-shan CUI Zhe CHEN Dong CHEN 王涵;章海明;崔振山;陈哲;陈东(上海交通大学材料科学与工程学院,上海200240)

机构地区：[1]School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《Transactions of Nonferrous Metals Society of China》2021年第5期1235-1248,共14页中国有色金属学报（英文版）

基　　金：the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2018-ZX04044001-008);the National Natural Science Foundation of China(No.52075328).

摘　　要：The hot forming behavior,failure mechanism,and microstructure evolution of in-situ TiB_(2)particle-reinforced 7075 aluminum matrix composite were investigated by isothermal compression test under different deformation conditions of deformation temperatures of 300−450℃ and strain rates of 0.001^(−1)s^(−1).The results demonstrate that the failure behavior of the composite exhibits both particle fracture and interface debonding at low temperature and high strain rate,and dimple rupture of the matrix at high temperature and low strain rate.Full dynamic recrystallization,which improves the composite formability,occurs under conditions of high temperature(450℃)and low strain rate(0.001 s^(−1));the grain size of the matrix after hot compression was significantly smaller than that of traditional 7075Al and ex-situ particle reinforced 7075Al matrix composite.Based on the flow stress curves,a constitutive model describing the relationship of the flow stress,true strain,strain rate and temperature was proposed.Furthermore,the processing maps based on both the dynamic material modeling(DMM)and modified DMM(MDMM)were established to analyze flow instability domain of the composite and optimize hot forming processing parameters.The optimum processing domain was determined at temperatures of 425−450℃ and strain rates of 0.001−0.01 s^(−1),in which the fine grain microstructure can be gained and particle crack and interface debonding can be avoided.采用等温热压缩实验研究不同变形条件下(变形温度300~450℃、应变速率0.001~1 s^(−1))原位TiB_(2)颗粒增强7075铝基复合材料的热成形行为、损伤机制和显微组织演变。结果表明,复合材料在低温和高应变速率下的主要损伤机制是颗粒断裂和界面脱粘,而在高温和低应变速率下主要是基体的韧窝断裂。此外,复合材料在高温、低应变速率变形条件下(变形温度450℃、应变速率0.001 s^(−1))出现完全动态再结晶,从而提高复合材料的热成形性。热压缩后原位TiB_(2)/7075Al复合材料的晶粒尺寸明显小于7075Al和非原位7075Al复合材料。根据流动应力实验曲线,建立原位TiB_(2)/7075Al复合材料包含流变应力、真应变、应变速率和温度的本构方程。基于动态材料模型(DMM)和改进的动态材料模型(MDMM)建立加工图,分析复合材料的流变失稳区和优化复合材料的热变形工艺参数。复合材料的最佳变形条件为变形温度425~450℃、应变速率0.001~0.01 s^(−1),在该变形条件下复合材料的晶粒得到细化,且不发生颗粒断裂和界面脱粘。

关 键 词：in-situ TiB2 particles aluminum matrix composite hot compression deformation particle fracture interface debonding dynamic recrystallization 

分 类 号：TB333[一般工业技术—材料科学与工程]