A strong and deformable in-situ magnesium nanocomposite igniting above 1000 °c

Abstract

Magnesium has been trending of late in automobile, aerospace, defense, sports, electronic and biomedical sectors as it offers an advantage in light-weighting. In aluminum, titanium, and steel dominated aerospace and defense sectors, applications of Mg were banned/restricted until recently due to perceived easy ignition and inability to self-extinguish immediately. Strength is generally inversely related to ductility, weak texture and unrelated to ignition resistance, making it challenging to optimize all four concurrently in a material. We address this challenge by designing a low density (~1.76 g.cm-3) in-situ Mg nanocomposite. It is a resultant of a sequence of in-situ reactions during melt processing and extrusion. The in-situ formed Y2O3 nanoparticles exhibit coherency with matrix and lead to development of large amount of elastic and plastic strain fields around them. These nanoparticles and secondary phases (Mg2Ca and Mg2Y) are responsible for the nanocomposite's high tensile strength (~343 MPa). A weak texture mediated tensile ductility of 30% and compressive failure strain of 44% is observed. Further, the ignition temperature increased to 1045 °C (near the boiling point of Mg) due to the formation of protective surficial oxide layers aided by the presence of insulating Y2O3 nanoparticles, rendering the nanocomposite outperform other traditional commercial Mg-based materials. © 2018 The Author(s).