采用拉伸测试、电导率测试和透射电镜等手段研究了双级时效制度对7150铝合金的力学性能、电导率和微观组织的影响.结果表明:在本研究范围内,第一级时效制度对合金的力学性能和电导率影响不大;合金经过120℃/8 h+160℃/6 h,可以达到与单级峰时效处理相当的抗拉强度,并且电导率有明显提高;第二级时效温度为168℃时效时,相比在160℃进行第二级时效,合金在具有同等电导率水平时,损失的强度相对较多,但时效时间明显变短;120℃/8 h+160℃/32 h双级时效后,合金的抗拉强度为560 MPa,屈服强度为520 MPa,延伸率为11.5%,电导率22.7 Ms·m~(-1),晶内沉淀析出相以η'和η为主,晶界析出相完全断开.
The effects of two-step aging treatment on the mechanical properties, electrical conductivity and microstructures of 7150 aluminum alloy were investigated by means of tensile, conductivity measurement and transmission electron microscopy. The results showed that the pre-aging had no obvious effect on the mechanical properties and electrical conductivity. The tensile strength could achieve the level of single-step peak aging by treatment of 120 ℃/8 h + 160 ℃/6 h, and with larger electrical conductivity. The aging temperature of the second step was 168 ℃, compared with 160 ℃, the alloy could achieve the same level of electrical conductivity, but the strength loss was larger and the aging time became shorter. The tensile strength, yield strength, elongation and electrical conductivity of the alloy were 560,520 MPa, 11.5 % and 22.7 MS·m~(-1) after two-step aging ( 120 ℃/8 h + 160 ℃/32 h), respectively. The precipi-tation phases in the matrix were η' and η mainly, and the precipitation phases on the grain boundaries were disconnected completely.
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