背应力平衡策略实现非均质Al-SiC复合材料的强塑性协同

Back stress dynamic balancing strategy enabled strength-ductility synergy in heterostructured Al-SiC composites

高强复合材料的低位错存储性能及其引发的强塑倒置问题阻碍了该系列材料的进一步发展.本文通过新颖的形变驱动冶金方法,设计了一种巧妙的具有粗细晶粒异质结构的纳微混合SiC增强铝基复合材料.基于背应力理论对累积的几何必须位错和晶内分散的SiC颗粒进行调控,使得背应力与外在施加应力保持动态平衡.这是本策略实现材料强塑性协同的关键.所设计的SiC_(5np-5μp)/Al复合材料的极限抗拉强度和均匀伸长率分别为324 MPa和12.9%,达到SiC_(10μp)/Al抗拉强度的181%,而塑性仅损失了约3%.因此,本文提供了一种基于背应力优化的强度-塑性协同新策略.

Strength-ductility trade-off dilemma remains a significant obstacle to high-strength composites due to the undesirable dislocation storability.Herein,an ingenious nano-micro SiC-reinforced Al matrix composite(AMC)with heterogeneous grain structures of coarse and fine grains was designed via a novel deformation-driven metallurgy method.The accumulated geometrically necessary dislocations and the intragranularly dispersed SiC particles were tailored based on the principle of back stress amelioration,which was a key point to maintain the dynamic balance with the applied stress toward strength-ductility synergy.The ultimate tensile strength and uniform elongation of the designed SiC_(5np-5μp)/Al composite reached 324 MPa and 12.9%,respectively,and the strength was 181%as high as that of the SiC_(10μp)/Al with only 3%ductility loss.As such,a new strategy was provided herein to promote strength-ductility synergy via the further modified back stress.