Microstructure of the Al-M-Ce (M = Ti, V, Cr) alloy system solidified under different cooling rates

Abstract

The search of the aeronautical industry for lower density components to increase the fuel energy efficiency has been focused, in the last years, in searching new high-temperature strength alloy systems. In this context, the Al-based alloys with formation of microstructures that result in high mechanical strength and high thermal stability, obtained by rapid solidification have been considered. The objective of this dissertation work is to investigate the microstructure of Al-(Ti, V, Cr)-Ce alloy systems solidified under different cooling rates, the thermal stability of the microstructure and the resulting hardness. This study will allow the selection of low density alloys for potential application at high temperatures (200°C to 400°C). Compositions of the Al- (M) -Ce ternary systems (where M = Ti or V or Cr) that lead to the formation of the Al20M2Ce phase, surrounded by different constituents, will be selected. Depending on both chemical composition and heat treatment, several microstructures will be obtained that result in different mechanical properties. The compositions selection for the three systems, i.e., Al-Ti-Ce, Al-V-Ce and Al-Cr-Ce, will be guided based on ternary diagrams available in the literature and in previous works with Mn. The cooling rate effect on phases formation for the selected compositions will be studied through production of samples by solid copper die casting with different cavity dimensions. The microstructures thermal stability evaluation will be performed through heat treatments between 200°C and 400°C, during different times (to be defined). The microstructures of the samples, both as cast and heat treated conditions, will be analyzed by different characterization techniques: X-ray diffraction, scanning electron microscopy and transmission electron microscopy. (AU)