Isothermal Oxidation of SLM fabricated Mo(Si1-xAlx)2-based composite

Abstract Near full dense C40 hexagonal structured Mo(Si1-xAlx)2-based composite coupons with 7 mm diameter by 7 mm height were prepared by selective laser melting (SLM) of MoSi2-30 wt.% AlSi10Mg powder mixture and subjected to isothermal oxidation. As a reference, MoSi2 bulk sample was prepared by spark plasma sintering (SPS) technique. The quantitative oxidation tests were conducted in dry air atmosphere at 500 °C for 72 and 120 hours with three specimens for each dwell time. The estimated weight change after 120 h oxidation accompanied with the SEM analysis revealed the slow oxidation of the SPS prepared MoSi2 bulk sample without evidence of pesting, however, the formed oxide layer was not protective and contained large cracks and multiple microcracks. The SLM produced sample showed remarkably slower oxidation rate as well as the formation of only a nanoscale oxide layer, highlighting the significant influence on Al additive to enhance MoSi2 oxidation resistance, thus making the developed material promising to be used as heating element.