TiC/AZ91D镁基复合材料高温压缩变形行为

COMPRESSIVE DEFORMATION BEHAVIOR OF TiC/ AZ91D COMPOSITES AT ELEVATED TEMPERATURES

利用自发渗透原位合成法制备了不同体积分数的TiC增强AZ91D镁基复合材料,研究了不同压缩应变速率以及不 同变形温度下复合材料的热变形行为,计算分析了不同温度下应变速率敏感指数(m)和表观激活能(Q)与TiC含量的关系.结 果表明: TiC／AZ91D复合材料压缩流变应力随TiC含量的增加而升高; TiC含量相同时,流变应力随温度升高或初始应变 速率减小而降低. m值随变形温度升高而增大;变形温度以及压缩应变速率相同时. m值随TiC含量升高而增大. Q值依 赖于温度、应变速率和TiC含量及其分布,不同条件下其高温变形机制有所差异.

In situ reactive infiltration technique was utilized to synthesis TiC particulate-reinforced magnesium matrix composites (TiC/AZ91D). The hot compressive behavior of as fabricated composites was studied at strain rates (epsilon) over dot 10(-3) - 10(-1) s(-1) and at temperatures of 573-723 K. The strain rate sensitivity exponent (m), apparent activation energy (Q) and their relations with TiC content and temperature were calculated and analyzed according to the true stress-true strain curves. The results show that the compressive flow stress of the composites increases with increasing the TiC content. For the same TiC content, the flow stress decreases with elevating deformation temperatures or with decreasing the initial strain rates. The m value increases with increasing temperature and at the same deformation temperature and strain rate, the m value increases with increasing the TiC content. The Q value depends on the deformation temperature, strain rate and TiC content and its distribution, and the composites exhibit different deformation mechanisms at elevated temperatures.