热处理对含微量镧AZ91镁合金组织和性能的影响

摘要

The influences of solution and aging treatments on microstructure and mechanical properties of AZ91 magnesium alloy with 0.164 8wt% La refined by vaccum process were studied by X-ray diffraction,scanning electron microscopy,energy dispersive spectroscopy,microhardness testing and so on.The results show that a great number of second β phases after solid（410 ℃×24 h air cooling） and aging treatments（170 ℃×30 h air cooling）.Compared with cast magnesium alloy,the tensile strength,yield strength,elongation and hardness of aged AZ91 magnesium alloy with La increased by 41.84%,65.08%,35.65%,47.62%,respectively.The reason was that the diffusion state of Al atoms was changed by trace La during heat treatment,and thus the morphology and distribution of first and second β-Mg17Al12 phases were controlled effectively.%用XRD、SEM、EDS和显微硬度仪等研究了固溶、时效处理对真空精炼的含0.164 8%（质量分数）镧AZ91镁合金显微组织和力学性能的影响。结果表明：加入微量镧后的AZ91镁合金在410℃×24h空冷固溶＋170℃×30h空冷时效后,第二类β相大量析出,且呈不连续层片状沿晶界两侧分布;时效态含镧AZ91镁合金的抗拉强度、屈服强度、伸长率和显微硬度分别比铸态不含镧AZ91合金的提高了41.84%,65.08%,35.65%和47.62%;其原因是微量镧改变了热处理中铝原子的扩散状态,有效控制了第一、二类β-Mg17Al12相析出时的形态与分布。