The Role of Technological Process in Structural Performances of Quasi-Crystalline Al–Fe–Cr Alloy

Abstract

The present study emphasizes the role of processing strategy in terms of its effect on structural performances, heat-treatment response, and mechanical behaviour of quasi-crystalline Al–Fe–Cr-based alloy with nominal composition Al94Fe3Cr3. Several kinds of semi-products and bulk-shaped materials, all processed with Al94Fe3Cr3 alloy, have been produced using rapid solidification by melt spinning, powder atomization, hot extrusion, and cold-spraying, respectively. All kinds of semi-products and bulk-shaped materials comprised nanosize quasi-crystalline particles of i-phase, all embedded in α-Al matrix, although fraction volume of quasi-crystals and other structural parameters were rather different and dependent on processing route. In particular, cold-spraying technique was believed to give essential advantage in retaining quasi-crystalline particles contained by feedstock powder as compared to currently employed hot extrusion. Crucial role of nanosize quasi-crystalline particles in structural performances and superior combination of high strength and sufficient ductility of ternary Al–Fe–Cr alloy was justified over evolution of mechanical properties under heating. In this aim, evolution of the structure and mechanical properties of each kind of Al94Fe3Cr3 alloy in response to heat treatment was examined and discussed by considering the classical strengthening mechanisms. A set of mechanical characteristics including microhardness, HV, yield stress, σy, Young’s modulus, E, and plasticity characteristic δH/δA was determined by indentation technique and used in consideration. Strength properties (HV, σy, E) and plasticity characteristic (δH/δA) of cold-sprayed Al94Fe3Cr3 alloy were revealed to be much higher than those provided by currently employed hot extrusion. The important point concerns the fact that cold-sprayed Al94Fe3Cr3 alloy kept almost stable values of mechanical properties at least up to 350 °C, suggesting potential application of this material in engineering practice under intermediate temperature.