Formation and mechanical properties of La–Al(–Ga)–C bulk metallic glasses with high content of carbon

Abstract

Rare earth metal-based bulk metallic glasses (BMGs) containing metalloid element are synthesized in La–Al(–Ga)–C alloy system by copper mold casting. The high glass-forming ability (GFA) of the La–Al–C alloys revealed by the critical diameters up to 3mm could be due to the large difference in atomic size besides the strong bonding among the constituent elements. By partial substitution of Al in the La–Al–C alloy with similar element Ga, the La–Al–Ga–C BMGs exhibited enhanced GFA and the critical diameters were up to 6mm. The mechanical properties including compressive mechanical behavior, hardness and notch fracture toughness of the La-based BMGs are investigated. The La60Al30C10 BMG exhibits compressive fracture strength of nearly 1GPa, which is the highest for the La-based BMGs. The mechanisms for the formation and mechanical properties of the La–Al(–Ga)–C BMGs are discussed. The La–Al(–Ga)–C BMGs with high content of element C and high strength could be model materials for fundamental research.