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Al-Cu-Mg系合金是靠时效强化提高耐热性,但这种强化作用在200℃以下较为适宜,如果,使用温度提高,耐热性明显下降.在250℃下进行持久试验发现:α(Al)过饱和固溶体已经分解,S(CuMgAl_2)相质点沿晶界析出;在300℃下,进行持久试验发现:S(CuMgAl_2)相大量析出,并聚集长大.这说明当温度达到250℃以上时,由于S(CuMgAl_2)相大量析出并聚集,合金的耐热性降低.而在Al-Cu-Mg系合金中,等量地加入Fe和Ni(0.8～1.2%),在基体内形成FeNiAl_9相,就能提高合金的耐热性.在250℃下,进行持久试验发现:FeNiAl_9相的形态无变化;在300℃下,进行持久试验发现:FeNiAl_9相的形态仍无变化.随着温度的升高,FeNiAl_9相的形态不发生变化,因而,对合金的耐热性有良好的作用.FeNiAl_9相就是起异相强化作用,试验表明:在Al-Cu-Mg系合金中,等量加入Fe和Ni,能使合金的高温性能提高2～4千克/毫米~2.
Al-Cu-Mg based alloys improve the heat resistance by age-hardening, but this strengthening effect is suitable below 200 ° C, and the use of Al-Cu-Mg alloys decreases the heat resistance remarkably at 250 ° C. (Al) supersaturated solid solution has been decomposed, S (CuMgAl_2) phase particles precipitated along the grain boundaries; at 300 ℃, the long-term test found that: S (CuMgAl_2) phase precipitation and aggregation of large growth .This shows that when the temperature reaches 250 ℃ , The heat resistance of the alloy decreases due to the precipitation and aggregation of S (CuMgAl 2) phases, whereas Fe and Ni (0.8-1.2%) are uniformly added to the Al-Cu-Mg based alloy to form in the matrix FeNiAl_9 phase, can improve the heat resistance of the alloy at 250 ℃, the lasting test found: FeNiAl_9 phase morphology no change; at 300 ℃, lasting test found: FeNiAl_9 phase morphology remains unchanged with the temperature , The morphology of FeNiAl_9 phase does not change, therefore, it has a good effect on the heat resistance of the alloy.FeNiAl_9 phase is the role of heterogeneous strengthening, the experiment shows that: in the Al-Cu-Mg alloy, the same amount of added Fe and Ni, the alloy can improve the high temperature performance of 2 to 4 kg / mm ~ 2.