Structures of melt-spun and high-energy ball milled Al3Ti-Mn-Nb intermetallic alloy

Because of their low density, relatively high melting point, high elevated temperature strength and excellent oxidation resistance, Al3Ti intermetallic is a good candidate to be exploited as the structural material for elevated temperature purpose. In this article, the structures and constituents of a quaternary alloy based on Al67Mn8Ti25 with 2 at% Nb addition prepared by melt-spinning and high-energy ball milling have been studied. The authors found that adding certain amounts of Nb into the single phase L12Al67Ti25Mn8 alloy can form a new type of Al3Ti-based alloy, which has the L12 matrix and DO22Al3(Ti,Nb) second phase in the cast state. Rapid solidification by melt spinning of this alloy is not effective for microstructural control. It is also composed of L12 matrix with the DO22 phase precipitated along the grain boundaries at the free side of the ribbon. In the case of high-energy ball milling, the second phase dissolves into the matrix, accompanying with the disordering of the L12 structure. When the milling time reaches 13 h, the structure is completely disordered, forming a FCC solid solution. By further milling to 30 h, the powder is purely amorphous