Ignition-resistant Mg-Ca-Y-(Al, Zn) alloys prepared by extrusion

Abstract This work focuses on novel magnesium alloys for potential use in the aerospace industry and their comprehensive characterisation. There are several criteria alloys must meet for aerospace applications, including adequate mechanical properties, acceptable cost, and high corrosion and flammability resistance. Based on these requirements, three novel magnesium alloys were designed: Mg-4Ca-1Y, Mg-4Ca-1Y-1Zn, and Mg-4Ca-1Y-1Al-1Zn (wt%), which were processed by extrusion. Their microstructure, mechanical properties, corrosion, and ignition resistance were subsequently analysed in detail. Extrusion processing produced an almost fully recrystallised microstructure with an average grain size below 2 µm in all investigated alloys. Mechanical characterisation by uniaxial compression and tensile testing coupled with digital image correlation, revealed high strength, with yield strengths above 270 MPa in both loading modes. The Mg-4Ca-1Y-1Al-1Zn alloy exhibited the highest tensile yield strength of 341 MPa, attributable to its dense secondary phase structure. However, the most favourable combination of strength and ductility was achieved in the Mg-4Ca-1Y-1Zn alloy, which displayed a tensile yield strength of 275 MPa and a high fracture elongation of 12%. Despite the low content of rare-earth elements, which were replaced by more affordable calcium, the alloys reached exceptionally high ignition temperatures (approximately 1100 °C), exceeding those of the expensive, heavily alloyed commercial WE43 alloy.