【摘要】 研究了不同回归再时效(RRA)制度对高Zn超高强铝合金的力学性能和微观组织的影响。研究结果表明:采用120 ℃×4 h预时效+回归30 min+120 ℃×24 h时效RRA处理时,可以使合金保持较高的强度,达到740~750 MPa,与T6态合金相比,其强度仅下降5%,晶内析出组织与T6 态合金的组织基本相似,而晶界析出相聚集、粗化,与过时效相似;随着回归时间延长,合金的强度逐渐下降,而延伸率略有提高;采用较高的时效温度130 ℃进行RRA处理时,虽然合金强度仍然能够保持在700 MPa以上,但是Ag的加入促进了较高温度下晶内粗大平衡相的析出,极大地降低了合金的塑性。更多还原

【Abstract】 The influence of different retrogression and reaging(RRA) heat treatments on the microstructure and mechanical properties of the high-zinc super-high strength aluminum alloy was discussed. The results show that the alloy maintains high tensile strength of about 740750 MPa after the RRA heat treatment of 120 ℃×4 h pre-ageing+retrogressed for 30 min+120 ℃×24 h re-ageing. The intracrystalline microstructure is similar to that of T6 temper and the grain boundary precipitate is similar to that of over-aged condition. With the retrogression time prolonged, the tensile strength of the alloy gradually decreases while the elongation ratio slightly increases. When ageing at a higher temperature of 130 ℃, the alloy after RRA treatment can obtain high tensile strength above 700 MPa, but the plasticity of the alloy decreases significantly due to the effect of small addition of silver which promotes the precipitation of coarse equilibrium phase.更多还原