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通过分级淬火方法测定了7050铝合金的TTT曲线,采用TEM和JMA方程等分析手段研究了固溶、等温淬火和时效过程中微观组织的演变规律及其动力学特性.结果表明,合金TTT曲线的鼻尖温度在330℃附近,淬火敏感区间为300~380℃,高温区(400~450℃)淬火敏感性低于低温区(210~270℃);等温保温过程中过饱和固溶体主要析出以Al3Zr粒子为形核核心的片层状h平衡相及少量针状S相,随保温时间延长析出相体积分数快速增加,同时在晶界排列变得连续而粗化、无沉淀析出带(PFZ)宽化,在远离鼻尖的温度下保温合金析出速率减慢,在晶界排布连续化和粗化程度降低;JMA方程中反映析出相形态的常数n在0.50~0.65的范围内,析出相特征以片层状相为主、针状相为辅.
The TTT curves of 7050 aluminum alloy were measured by graded quenching method. The evolution and the dynamics of microstructure in solution, austempering and aging were studied by means of TEM and JMA equations. The results showed that the TTT curves The tip temperature of the tip is about 330 ℃, the sensitivity range of quenching is 300 ~ 380 ℃, and the sensitivity of quenching in the high temperature range (400 ~ 450 ℃) is lower than that in the low temperature range (210 ~ 270 ℃) For the lamellar h-phase and a small amount of acicular S-phase in the nucleus, the volume fraction of precipitated phase increases rapidly with the increase of holding time, and the grain boundaries become continuous and coarser without PFZ broadening , At a temperature far from the tip of the nose, the precipitation rate of the heat-retaining alloy slowed down and the continuity at the grain boundary and the degree of roughening decreased. The constant n in the JMA equation reflecting the morphology of precipitates was in the range of 0.50-0.65. Lamellar phase, acicular phase supplemented.