Effects of Ce and Ti on the microstructures and mechanical properties of an AlCuMgAg alloy.pdf

RARE METALS Vol. 26, No. 1, Feb 2007, p. 28 E-mail: rm@ Effects of Ce and Ti on the microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy SONG Min, CHEN Kanghua, and HUANG Lanping State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China (Received 2005-11-25) Abstract: The effects of Ce and Ti additions on the microstructures and mechanical properties of an Al-Cu-Mg-Ag alloy have been studied. It has been shown that either Ce or Ti can decrease the as-cast grain size of the Al-Cu-Mg-Ag alloy, in- crease the nucleation ratio for Ω phase as heterogeneous nucleation centers, inhibit the growth of Ω phase during aging, and thus increase the volume fraction and decrease the spacing of Ω phase. These microstructures increase the yield strength and tensile strength. However, if both Ce and Ti are added to the alloy, they form (Ce,Ti)-contained compounds and increase the grain size during casting, but have no effects on the nucleation and the growth of Ω phase during aging. The alloy contain- ing both Ce and Ti has a relatively lower Vicks hardness and strength compared to the alloy containing either Ce or Ti. Key words: Al-Cu-Mg-Ag alloy; microstructures; mechanical properties; Ce; Ti; Ω phase [This study was financially supported by the State Key Fundamental Research Project on Al, China (No. 2005CB623704).] 1. Introduction strengthening phase in aluminum alloys for applica- tions at elevated temperature. Heat-treated aluminum alloys are required for Ti was widely used as an element to decrease the several structural applications. Several efforts have as-cast grain size in aluminum alloys. A previous been made to improve the mechanical properties of study indicated that rare earth element Ce can im-