Strengthening and toughening of Mg–Cu–(Y, Gd) bulk metallic glasses by minor addition of Be

Mg65Cu25Re10 and Mg65Cu24Be1Re10 (Re = Y, Gd) bulk metallic glasses (BMGs) were successfully fabricated by conventional Cu-mold casting method. By the addition of 1 at.% Be, the compressive strengths of Mg65Cu24Be1Y10 and Mg65Cu24Be1Gd10 alloys are increased from 760 MPa and 860 MPa to 930 MPa and 1025 MPa, respectively. The fracture morphology is changed from nanometer scale corrugation to micrometer scale dimple and vein pattern, indicating that the addition of minor Be obviously improves the toughness of the alloys. The fracture morphologies with different size of plastic zone in Mg-based BMGs provide probability for understanding the fracture mechanism of BMGs.