Hot Deformation Behavior and Workability of （SiCp ＋ Mg2B2Osw）/6061 AI Hybrid and SiCp/6061 AI Composites

• Published in: 金属学报：英文版 2014 (1), p.63-74
• Main Author: M. Wang P. Jin J. Wang L. Han C. Cui
• Format: Article
• Language: English
• Subjects: SiC颗粒; 加工性能; 应变速率; 混合动力; 混杂复合材料; 热变形行为
• ISSN: 1006-7191; 2194-1289

The hot deformation behavior of （3 vol% SiCp -4- 3 vol% Mg2B2Osw）/6061 A1 （W3P3） hybrid composite and 6 vol% SiCp/6061 A1 （P6） composite have been characterized in the temperature range of 300--450 ℃ and strain rate range of 0.0001-0.1 s-1 using isothermal constant true strain rate tests. The flow behavior and processing maps have been investigated using the corrected data to eliminate the effect of friction. Under the same deformation conditions, the compressive resistance of the singular composite remains superior to that of the hybrid composites. The processing map of W3P3 hybrid composite exhibits a single hot working domain at the temperature between 350 and 450 ℃ with strain rate between 0.0001 and 0.003 s-1 （domain A）. Two hot working domains exist for P6 composite： （i） 300-400 ℃/ 0.0001-0.003 s-1 （domain B1）; （ii） 380-450 ℃/0.01-0.1 s-1 （domain B2）. The processing maps also reveal the flow instability of the two composites, which is associated with whiskers breakage, whisker/matrix interfacial debonding, SiCp/ matrix interfacial decohesion, adiabatic shear bands or flow localization, and wedge cracking in the corresponding regions. The estimated apparent activation energies are about 224 kJ mo1-1 in domain A for W3P3 hybrid composite, 177 kJ mo1-1 in domain B1 and 263 kJ mo1-1 in domain B2 for P6 composite, respectively. These values are higher than that for self-diffusion in A1 （142 kJ mol-1）, suggesting that there is a significant contribution from the back stress caused by the presence of particles and/or whiskers in the matrix. The deformation mechanisms corresponding to domain B 1 and domain B2 are dislocation climb controlled creep and cross-slip for P6 composite, respectively. For W3P3 hybrid composite, the deformation mechanisms contain dislocation climb controlled creep and grain boundary sliding caused by DRX in domain A.