固溶处理后的不同淬火过程对7050合金性能及析出行为的影响

摘要

The effects of quenching in different ways following solid-solution treatment on properties and precipitation behaviors of 7050 alloy were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), selected area electron diffraction (SAED), hardness and electrical conductivity tests. Results show that after quenching in different ways, electrical conductivity of the alloy decreases rapidly in the first 48 h of natural aging. The electrical conductivity of 7050 alloy in natural aging state is determined by the size and density of GP zones, and the size of GP zones is the main factor. After natural aging for 70 d, the size of GP zones is 1.8-2.6 nm in matrix of the immersion quenched sample and it is 1.4-1.8 nm in matrix of both water mist and forced air quenched samples. After natural and artificial peak aging, the hardness of the water mist quenched sample is HV 193.6 and its electrical conductivity is 30.5％ (IACS) which are both higher than those of the immersion quenched sample. Therefore, water mist quenching is an ideal quenching method for 7050 alloy sheets after solid-solution treatment.%采用扫描电镜(SEM)、透射电镜(TEM)、选区电子衍射(SAED)、硬度及电导率测试等手段,研究7050合金薄板固溶处理后通过不同方式淬火冷却至室温的性能及析出行为.结果表明:7050合金经不同方式淬火冷却后,在自然时效最初的48 h内样品的电导率迅速下降.合金自然时效状态的电导率由GP区的尺寸和密度共同决定,其中GP区的尺寸为主要影响因素.室温水淬火样品基体内GP区的尺寸最大,为1.8～2.6 nm;水雾和强风淬火样品基体内的GP区尺寸相近,为1.4～1.8 nm.水雾淬火为7050合金固溶处理后较理想的淬火冷却方式,由该方式淬火的7050合金先自然时效70 d再人工峰时效处理后的硬度为HV 193.6,电导率为30.5％(IACS),均高于相同状态下室温水淬火合金的.