Microstructural Variations in Laser Powder Bed Fused Al-15%Fe Alloy at Intermediate Temperatures

The samples of the Al-15Fe (mass%) binary alloy that were additively manufactured by laser powder bed fusion (L-PBF) were exposed to intermediate temperatures (300 and 500 degrees C), and the thermally induced variations in their microstructural characteristics were investigated. The L-PBF-manufactured sample was found to have a microstructure comprising a stable theta-Al13Fe4 phase localized around melt-pool boundaries and several spherical metastable Al6Fe-phase particles surrounded by a nanoscale alpha-Al/Al6Fe cellular structure in the melt pools. The morphology of the theta phase remained almost unchanged even after 1000 h of exposure at 300 degrees C. Moreover, the nanoscale alpha-Al/Al6Fe cellular structure dissolved in the alpha-Al matrix; this was followed by the growth (and nucleation) of the spherical Al6Fe-phase particles and the precipitation of the theta phase. Numerous equiaxed grains were formed in the alpha-Al matrix during the thermal exposure, which led to the formation of a relatively homogenous microstructure. The variations in these microstructural characteristics were more pronounced at the higher investigated temperature of 500 degrees C.

Automated summary

The thermally induced variations in microstructural characteristics of Al-15Fe binary alloy samples fabricated by L-PBF at intermediate temperatures were investigated. The microstructure consisted of stable theta-Al13Fe4 phase, spherical metastable Al6Fe-phase particles, and nanoscale alpha-Al/Al6Fe cellular structure. The alpha-Al/Al6Fe cellular structure dissolved, followed by growth and precipitation of particles, and formation of equiaxed grains during thermal exposure. These changes were more pronounced at higher temperature.