Calorimetric study of Ni3Al alloys produced by rapid solidification

In the present study, Ni3Al alloys were produced by fast solidification through melt spinning. The aim of the present work is to determine the main mechanisms present in the ordering process of these alloys when submitted to a cycle of continuous heating, as well as the influence of the chemical composition in those ordering processes. The method applied to reach these results was DSC. During the processes of heating of Ni3Al alloys three exothermic reactions were observed, which can be associated in the following sequence: vacancy annihilation; ordering and grain growth. In all reactions, the enthalpy involved increases with the increase of Nickel content in the alloy. This fact can be associated with microstructural factors, because the Ni3Al rapidly solidified alloys presenting a characteristic bimodal distribution of ordered domains. Increasing Nickel in the alloy results in a consequent growth of the fraction of fine ordered domains.