相溶解协同提升高熵合金的强度和塑性

Phase dissolution strengthens and ductilizes a high-entropy alloy

热处理是金属材料热机械加工的常用手段.随着热处理温度的升高而湮灭的缺陷通常导致材料的塑性提升而强度降低.本研究中,我们通过提高热处理温度促进相溶解而协同提升了TiZrNbTa高熵合金的强度和塑性.当热处理温度从800提升至1250°C,合金的拉伸屈服强度提高了40%,达到1003±16 MPa.同时,合金的伸长率增加了近一倍,达到16.79%±1.03%.热处理温度提升引起的相溶解加剧了晶格畸变,从而增强了晶格摩擦应力并提升了屈服强度.相溶解也降低了界面失配并缓解了应力集中.此外,1250°C热处理合金中的局部化学有序结构促进了位错共平面滑移和位错增殖.两种机制共同提升了合金的塑性.该研究不仅扩展了关于金属材料中热处理和相溶解的理解,而且也为合金的强韧化设计提供了思路.

Annealing is widely used in the thermomechanical processing of metallic alloys. Usually, ductility enhances while strength decreases because defects annihilate with the increase in annealing temperature. Here, we report a simultaneous improvement in strength and ductility of a TiZrNbTa high-entropy alloy by promoting phase dissolution with increasing annealing temperature. When annealing is performed from 800 to 1250℃, the tensile yield strength increases by 40% to 1003 ± 16 MPa, and the elongation is nearly doubled to 16.79% ± 1.03%. The annealing-induced phase dissolution promotes lattice distortion, contributing to enhanced lattice friction stress and yield strength. The correspondingly decreased interface mismatch alleviates stress concentration, and the stimulated formation of local chemical orders encourages coplanar slip and dislocation multiplication. Both occurrences boost ductility. These results not only expand our understanding of the phase dissolution and annealing effect in metallic materials, but also provide an insight into designing strong and ductile alloys.