Significant TRIP-effect improvement by manipulating ZrCu-B2 distribution in ZrCuAlCo-based bulk metallic glass composites via inoculating Ta particles

The ZrCu-B2 phase can effectively increase the plasticity for some specified Zr based metallic glasses composite (BMGC) by transformation induced plasticity (TRIP) mechanism. However, large and non-uniformly distributed ZrCu-B2 phases usually precipitate in the Zr-based BMGC samples by conventional copper mold casting. Therefore, the concept of inoculation in conventional solidification process was applied to modify the size and distribution of ZrCu-B2 phase in this study. Ta particles (size of 5-30 μm) with 0-4.0 vol% were added into the Zr48Cu47·5Al4Co0.5 BMG matrix as the inoculant. Ta particles can act as nucleation seeds for precipitating a homogeneously distributed ZrCu-B2 phase in the matrix. Moreover, the ZrCu-B2 precipitate size can be further controlled by different solidification cooling rates. It is clearly to see that the ZrCu-B2 phase embedded in the amorphous matrix for the Zr48Cu47·5Al4Co0.5 cast rods added with 0-0.75 vol% Ta particle cast by a copper mold at −30 °C (243 K, or a cooling rate of 650 K/s). In addition, the ZrCu-B2 phase exhibits a round shape and relatively homogeneous distribution. The optimum processes BMGC can exhibit significantly improved mechanical properties (1890 MPa fracture stress and 14% plastic strain) in comparison with the base BMGC (1560 MPa fracture strength and 7.5% plastic strain).