An Al-5Fe-6Cr alloy with outstanding high temperature mechanical behavior by laser powder bed fusion
M.T. Pérez‐Prado, Arturo Martín, Dongfeng Shi, Srdjan Milenković, C.M. Cepeda-Jiménez
Abstract
This research aims to study the laser powder bed fusion (L-PBF) processability, the microstructure and the tensile mechanical properties of an AlFeCr alloy at a wide range of temperatures. With this goal, Al-5Fe-6Cr (wt%) pre-alloyed powder was produced by casting and gas atomization. The microstructure of the as-atomized powders and the as-built specimens was characterized via scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. Following a parameter optimization study, dense as-built specimens with a high relative density of 99.8% and a Vickers hardness at room temperature of 192 HV were fabricated. In addition, the newly developed AlFeCr alloy exhibits yield strength values of 273 ± 5 MPa and 179 ± 3 MPa at 300ºC and 400ºC, respectively. The exceptional strength of this alloy at high temperature is attributed to the homogeneous precipitation during processing of large density of nanoscale icosahedral (i-phase) and intermetallic phases, which are endowed with high thermal stability. These values are significantly higher than those corresponding to the conventional wrought Al7075 aluminum alloy in the T6 condition and to all Al alloys manufactured by L-PBF to date. The current research sheds guidelines for the design of high strength aluminum alloys containing transition alloying elements that are suitable to be processed by L-PBF for high temperature structural applications in a cost effective way.