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在Mg9AlZnY合金基础上添加不同含量Gd元素,采用消失模铸造成形,研究其组织性能变化。结果发现,随着Gd含量的增加,Mg9AlZnY合金中的β-Mg17Al12相形成数量显著减少,并由连续网状结构转变为断续状和颗粒状结构。含Gd的Mg9AlZnY合金组织主要由α-Mg固溶体、β-Mg17Al12相和分布在α-Mg晶界的少量棒状Al2Y相和块状Al2Gd相组成。Al2Y和Al2Gd相热稳定性好,在高温下对晶界具有钉扎作用,防止晶界滑移,提高了晶界的高温强度。当Gd含量在0.9%(质量分数)左右时,经T6热处理后室温的抗拉强度为235MPa,200℃高温抗拉强度为156MPa,分别比Mg9AlZnY合金提高了11.9%和28.9%。
On the basis of Mg9AlZnY alloy, Gd elements with different contents were added, and the formation of the Gd was carried out by the lost foam casting. The microstructure and properties were studied. The results show that with the increase of Gd content, the amount of β-Mg17Al12 phase in Mg9AlZnY alloy decreases remarkably, and it changes from continuous network structure to discontinuous and granular structure. The microstructure of Gd-containing Mg9AlZnY alloy is mainly composed of α-Mg solid solution, β-Mg17Al12 phase and a small amount of rod-shaped Al2Y phase and bulk Al2Gd phase distributed in the α-Mg grain boundary. The Al2Y and Al2Gd phases have good thermal stability, pinning the grain boundaries at high temperatures, preventing grain boundary slip and increasing the high temperature strength at grain boundaries. When the Gd content is about 0.9% (mass fraction), the T6 heat treatment at room temperature after the tensile strength of 235MPa, 200 ℃ high temperature tensile strength of 156MPa, respectively, than the Mg9AlZnY alloy by 11.9% and 28.9%.