Processability of recycled quasicrystalline Al-Fe-Cr-Ti composites by selective laser melting - A statistical approach

Abstract

In situ Al-matrix quasicrystalline Al-Fe-Cr-Ti composites produced using recycled material were processed by selective laser melting (SLM). Three Al-Fe-Cr-Ti compositions (Al95Fe2Cr2Ti1, Al93Fe3Cr2Ti2, Al91Fe4Cr3Ti2) were gas atomized and, the powders range <75 µm, was used to produce SLM samples, where laser power and scan speeds were variated. The samples produced were analyzed by Optical and Scanning Electron Microscopy and Vicker hardness. The influence of the laser power and scan speed on the porosity, molten pool dimensions, structural characteristics of the in situ composite produced, and microhardness, was statistically interpreted using Pareto charts and main effects graphs. The three atomized powders presented similar physical characteristics and different microstructures; the higher the Fe, Cr, and Ti content, the higher the amount of quasicrystalline/approximant phases. By processing these powders by SLM, the processing window showed to become narrower with increasing the Fe, Cr, and Ti content. The laser power performs a dominant influence on the porosity of the SLMed samples; the higher the laser power, the higher the samples’ porosity. The length of the molten pools is mainly affected by the scan speed, while the depth is more dependent on the laser power. The largest molten pools dimensions were obtained under high laser power (> 250 W) or low scan speed (< 300 mm/s). Furthermore, laser power is the main factor for varying the cooling rates as, a consequence, the SLMed composites’ microstructure is varied, which directly influences the microhardness. These findings provide an effective way to fabricate tailored Al-Fe-Cr-Ti composites’ parts by SLM.