Mg-8.07Al-0.53Zn-1.36Nd轧制镁合金热处理过程中静态沉淀、再结晶及织构演变研究

Study on static precipitation、recrystallization and texture evolution of Mg-8.07Al-0.53Zn-1.36Nd rolled magnesium alloy during heat treatment

摘要:

采用SEM、EBSD、EDS等测试方法对不同热处理温度下Mg-8.07Al-0.53Zn-1.36Nd镁合金微观组织及织构进行表征。结果表明：热处理后的合金主要由α-Mg基体、β-Mg₁₇Al₁₂沉淀以及含Nd化合物组成。400℃以下热处理后的合金中存在β-Mg₁₇Al₁₂沉淀析出区域和无析出区域双峰组织,主要沿变形带和孪晶界面析出的大量纳米级颗粒状β-Mg₁₇Al₁₂沉淀先于α-Mg基体静态再结晶的形成。升高退火温度,β-Mg₁₇Al₁₂数量变少,稀土相尺寸数量未有明显变化,双峰组织中的β-Mg₁₇Al₁₂沉淀无析出区域优先发生静态再结晶,这表明沉淀颗粒能够延缓静态再结晶。400℃热处理后的合金中β-Mg₁₇Al₁₂沉淀溶解、数量显著减少,镁基体发生完全再结晶且再结晶晶粒明显长大。EBSD结果显示,热处理后的实验合金织构主要以弱化的基面织构为主,并伴有部分非基面织构,400℃以下热处理的合金中,数量较多的β-Mg₁₇Al₁₂沉淀对弱化基面织构具有重要作用。随着热处理温度的升高,合金中位错密度下降,主要织构组分由{0001}<10-10>形变织构向{0001}<11-20>再结晶织构转变。

Abstract:

_{: Themicrostructure and texture of Mg-8.07Al-0.53Zn-1.36Nd magnesium alloy were characterized by SEM、EBSD and EDS.The results show that the heat-treated alloy is mainly composed of α-Mg matrix, β-Mg17Al12 precipitates and Nd-containing compounds. The bimodal grain structure ofβ-Mg17Al12 precipitates zones andfree zonein the alloy after heat treatment below 400℃. A large number of nanoscale granular β-Mg17Al12 precipitates mainly along the deformation zone and twin interface are precipitated first,andthen the static recrystallization of α-Mg matrix formed. With the increasing of annealing temperature, the amount of β-Mg17Al12 decreases, and the size and amount of rare earth phaseshaven’tbeen changed significantly. The static recrystallization occurs preferentially in the precipitates-free zones ofβ-Mg17Al12 precipitates in bimodal grain structure, which indicates that the precipitation particles can delay the static recrystallization. Theβ-Mg17Al12 precipitates in the alloy after heat treatment at 400℃ are dissolved and the amount is reduced significantly.The magnesium matrix recrystallized completely and the recrystallized grains grew up significantly. EBSD results show that the texture of the experimental alloy after heat treatment is mainly weakbasal texture, accompanied by part of the non-basal texture. In the alloy after heat treatment below 400℃, a large number of β-Mg17Al12 precipitates play an important role in weakening basal texture. With the increasing of heat treatment temperature, the dislocation density in the alloy decreases, and the main texture components change from {0001}< 10-10 > deformation texture to {0001}< 11-20 > recrystallization texture.}