Formation, microstructure, and mechanical properties of in situ Mg-Ni-(Gd,Nd) bulk metallic glass composite

摘要

Based on a ternary Mg_(75)Ni_(15)Gd_(10) metallic glass former, a new Mg_(80)Ni_(12)Gd_4Nd_4 bulk metallic glass composite (BMGC) was developed by tailoring the compositions of Mg and rare earth (RE) elements. This BMGC displayed compressive ultimate strength over 900 MPa with a total strain to failure of 4.3% and specific strength of 3.12 × 10~5 Nm/kg. The improved mechanical properties were attributed to a "dual phases" structure consisting of Mg solid solution flakes and glassy matrix in the Mg_(80)Ni_(12)Gd_4Nd_4 BMGC. The homogeneously dispersed Mg phases reinforcement in the BMGC were characterized as a long period ordered structure (LPOS) with periodic arrays of six close-packed planes distorted from the ideal hexagonal lattice of 6H-type. The LPOS-Mg in the composite can act as a soft media to trap or interact with the unstable shear bands and contribute to plastic strain. The present study may provide a guideline for designing the Mg-TM-RE-based (TM: transition metals) BMGCs with "dual phases" structures.