Design,Preparation And Properties Of Al-Cu-Ni Cast Heat-Resistant Alloys

In recent years,as the service temperature of automobile engines continues to increase,the high-temperature performance of traditional commercial cast aluminum alloys has been difficult to meet demand.Therefore,it is particularly important to develop new cast heat-resistant aluminum alloys.The work of this paper is centered on the high-temperature strength improvement of cast aluminum alloy.In this paper,guided by JMatPro thermodynamic calculations and phase diagrams,with the help of OM,DSC,XRD,SEM,and CT,the effects of alloying and heat treatment on the structure and properties of Al-Cu alloys were systematically explored.Firstly,based on Al-Cu-Ni alloy,the influence of different ratios of Cu and Ni on the microstructure and mechanical properties of the alloy was explored.Subsequently,Fe was added into the Al-6Cu-3.5Ni base alloy to strengthen the mechanical properties by T-Al₉FeNi with excellent thermal stability.At the same time,the changes in the structure and properties of Al-6Cu-3.5Ni-xFe alloy before and after heat treatment were also studied.Then Gd and Y were added to control the solidification process and microstructure of Al-6Cu-3.5Ni-0.8Fe alloy and optimize the high-temperature performance of the alloy.Finally,with the help of the Avizo software,the 3-D morphology of intermetallics in the alloy was quantitatively characterized,and the strengthening effect of the 3-D network structure on the high-temperature performance of the alloy was preliminary analyzed.Finally,a cast Al-6Cu-3.5Ni-0.8Fe-0.4Gd heat-resistant aluminum alloy was prepared based on two strengthening methods of 3-D network structure control and alloying.The tensile strength,yield strength,and elongation of the alloy at 350℃under as-cast conditions were 74.1MPa,61.2MPa,and 15.5%respectively.At the same time,combined with volume fraction,interconnectivity,and curvature,the strengthening effect of intermetallics’3-D network structure on the high-temperature properties of the alloy was initially revealed.