| Al-Cu-Mg alloys have many excellent performances,such as high strength,high elastic modulus.They are widely used in space flight and aviation as new structural materials.The effects of high temperature-short time aging treatment and micro-alloying on the room mechanical properties,fatigue crack propagation,thermal stability and microstructure evolution have been investigated.The modern analysis(HRTEM and 3DAP analysis)techniques were used to investigate the fatigue crack propagation,thermal stability of high temperature-short time aged 2524 aluminum alloy and the effect of the cyclic stress located in the fatigue tip on the fatigue crack growth rate. The results are:The hardening microstructure-GPB zones size of 2524 aluminum alloy are obtained by high temperature-short time artificial aging treatment(170℃/30min)is lager than that by natural aging treatment.The high temperature-short time artificial aging treatment can restrain the degradation of GPB zones.The fatigue crack growth of high temperature-short time artificial aged samples was decreased.The larger GPB zones obtained by artificial treatment are hard to redissolve,that retard the cyclic softening effect in the alloy.Further more,the fatigue crack propagation resistance is enhanced.Ag has played different roles in the mechanical properties of 2524 aluminum alloy with trace addition of Ag.In the nature aged and artificial aged alloys,there are no distinct precipitates in the matrix,but there are different precipitations in the matrix after thermal exposure treatments because of different solute clusters obtained after different aging treatment.It can enhance the mechanical properties and thermal stabilities of 2524+Ag alloy by changing the Cu content and Cu/Mg ratio.The properties of 0701 alloy which has a lower Cu content are higher than that of 2524+Ag alloy no matter under what heat treated and whether thermal exposed.Even more,the properties of 0626 alloy has a higher Cu/Mg ratio is the best in the three of alloys. |
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