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

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 3 mm 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 6 mm. The mechanical properties including compressive mechanical behavior, hardness and notch fracture toughness of the La-based BMGs are investigated. The La ₆₀Al₃₀C₁₀ BMG exhibits compressive fracture strength of nearly 1 GPa, 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.