Effect of alloying elements on thermal stability of nanocrystalline Al alloys

Abstract

Abstract The effect of incorporating limited-diffusivity elements such as Fe and Ti on thermal stability of the nanocrystalline Al alloy was investigated. Al−10wt.%Fe and Al−10wt.%Fe−5wt.%Ti alloys were fabricated. The initial mixtures of powders were milled for 100 h in vacuum. The bulk samples were fabricated from the milled powders in a high frequency induction heat sintering (HFIHS) system. The milled powders and the bulk sintered samples were characterized by X-ray diffraction (XRD), Vickers microhardness, field emission scanning electron microscopy (FESEM-EDS) and transmission electron microscopy (TEM). The observations indicated that Fe and Ti were completely dispersed in the matrix to form a supersaturated solid solution (SSSS) with Al. Additionally, the inclusion of alloying elements led to an increase in hardness and yield strength of the alloy by 127% and 152%, respectively. The elevated temperature compression tests were carried out to evaluate the thermal stability of the alloys. The Al−10wt.%Fe−5wt.%Ti alloy revealed the optimum thermally stable behavior of the three alloys studied. The incorporation of Fe and Ti improved the thermal stability of the developed alloys through inhibiting the grain growth, hindering dissolution and growth of second phases (such as Al13Fe4 and Al13Ti), and forming a stable solid solution.