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

Based on a ternary Mg₇₅Ni₁₅Gd₁₀ metallic glass former, a new Mg₈₀Ni₁₂Gd₄Nd₄ 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 × 10⁵ Nm/kg. The improved mechanical properties were attributed to a “dual phases” structure consisting of Mg solid solution flakes and glassy matrix in the Mg₈₀Ni₁₂Gd₄Nd₄ 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.