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比较了Mg-Gd-Y-Nd-Zr耐热镁合金变形后及经T5和T6处理后的组织演变。在热塑性变形过程中,合金组织内部同时发生动态再结晶和动态析出,晶粒内发生的动态析出降低了再结晶形核的驱动力,部分抑制了动态再结晶的发生。研究表明,该Mg-Gd-Y-Nd-Zr耐热镁合金综合力学性能经T5热处理后比T6热处理有显著提高。经T5处理后,抗拉强度提高到359.3 MPa,比T6处理后增加约48.5%;伸长率由5.17%增加到6.5%。显微组织的演变表明,峰值时效后,合金内部主要析出β′相,该析出相能对合金的晶界起到明显的钉扎作用,阻碍长时间时效过程中的晶粒长大。同时细小的β′析出相的第二相强化作用使其强度明显提高。
The microstructure evolution of Mg-Gd-Y-Nd-Zr heat-resistant magnesium alloy after deformation and T5 and T6 treatment was compared. During the process of thermoplastic deformation, dynamic recrystallization and dynamic precipitation occur simultaneously in the microstructure of the alloy. The dynamic precipitation in the grain decreases the driving force of recrystallization nucleation and partially inhibits the dynamic recrystallization. The results show that the mechanical properties of the Mg-Gd-Y-Nd-Zr heat-resistant magnesium alloy after T5 heat treatment than the T6 heat treatment significantly increased. After T5 treatment, the tensile strength increased to 359.3 MPa, an increase of about 48.5% after T6 treatment; the elongation increased from 5.17% to 6.5%. The evolution of microstructure shows that the β ’phase is mainly precipitated inside the alloy after the peak aging, and the precipitated phase can obviously pin the grain boundary of the alloy and hinder the grain growth during aging. At the same time, the strengthening effect of the second phase of the fine β ’precipitation phase increases obviously.