作　　者： ; ; ; ; ; ;

机构地区： 中南大学材料科学与工程学院

出　　处： 《中国有色金属学报》 2008年第10期1781-1787,共7页

摘　　要： 通过对不同热暴露制度下合金的常温拉伸力学性能测试和微观组织演变的观察,分析热暴露制度对7475-T7351铝合金微观组织和性能的影响。结果表明,热暴露温度和时间不同,对合金力学性能的影响也不同。当热暴露温度超过7475-T7351合金末级时效温度163℃时,合金强度明显下降而塑性明显提高,175℃热暴露100和500h后,合金强度分别下降29.7%和40.4%;当热暴露温度低于末级时效温度时,如果热暴露时间比较短,合金力学性能变化不大,但是如果热暴露时间很长,合金强度也下降而塑性也有所上升。125℃热暴露100和500h后合金强度分别下降0.9%和3.2%,150℃热暴露100和500h后合金强度分别下降11.4%和19.0%。热暴露条件下7475-T7351合金力学性能衰退的主要原因是晶内主要强化相η′(MgZn2)粗化以及晶界附近的无沉淀析出带(PFZ)的宽化。 The microstructures and tensile properties at different thermal exposure condition of 7475-T7351 alloy were studied by means of tensile test, OM and TEM analysis. The results show that when the thermal exposure temperature is higher than the second aging temperature of 7475-T7351 alloy, the strength drops dramatically and the elongation increases. When the alloy is thermal-exposed at 175 ℃ for 100 and 500 h, the strength decreases 29.7% and 40.4%, respectively. When the thermal exposure temperature is lower than the second aging temperature of the alloy and thermal exposure time is not so long, the tensile properties of the alloy have no change, but if the thermal exposure time is long, the tensile properties of the alloy will also decrease and the ductility also increase. For example, when 7475-T7351 alloy is thermal-exposed at 125 ℃ for 100 and 500 h, the strength decreases 0.9% and 3.2%, respectively, but when it is exposed at 150℃ for 100 and 500 h, the strength drops 11.4% and 19.0%, respectively. Coarsening of η＇ （MgZn2） precipitates and widening of precipitate-free-zones （PFZ） should be responsible for the decay of 7475-T7351 alloy during thermal exposure condition.

关 键 词： 铝合金 热暴露 力学性能 显微组织

领　　域： [金属学及工艺] [一般工业技术] [金属学及工艺]