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基于回归再时效(RRA)工艺,提出一种新的回归-应力时效制度(RSA)用于Al-Zn-Mg-Cu合金。系统研究了应力时效制度(时效时间和应力)对回归态Al-Zn-Mg-Cu合金析出相的影响。透射电镜(TEM)观察结果表明:在回归处理后,合金内部存在大量的基体析出相(MPts)和轻微不连续的晶界析出相(GBPsi时效时间和应力对回归态合金析出相的影响十分显著。随着时间和应力的增加,基体析出相的尺寸增加而密度减少;同时,晶界析出相的尺寸、间距和无沉淀的宽度也增加。相比于回归再时效工艺,回归-应力时效工艺使得晶内析出相尺寸增加,无沉淀析出带变窄且晶界析出相更不连续。
Based on regression re-aging (RRA), a new regression-stress aging (RSA) method was proposed for Al-Zn-Mg-Cu alloys. The effects of stress aging (aging time and stress) on the precipitation of the as-cast Al-Zn-Mg-Cu alloy were studied systematically. Transmission electron microscopy (TEM) results show that there are a large number of MPts and slightly discontinuous grain boundary precipitates in the alloy after the regressive treatment (GBPsi aging time and stress have significant effects on precipitated phases of the recalcitrant alloys .With the increase of time and stress, the size of precipitation phase of the matrix increases and the density decreases, meanwhile, the size, pitch and precipitation-free width of precipitation phase also increase.Compared with regression re-aging process, the regression-stress aging process The size of precipitation phase increases, the precipitation-free zone becomes narrower and the grain boundary precipitation phase is more discontinuous.