Local melting to design strong and plastically deformable bulk metallic glass composites

Abstract

Recently, CuZr-based bulk metallic glass (BMG) composites reinforced by the TRIP (transformation-induced plasticity) effect have been explored in attempt to accomplish an optimal of trade-off between strength and ductility. However, the design of such BMG composites with advanced mechanical properties still remains a big challenge for materials engineering. In this work, we proposed a technique of instantaneously and locally arc-melting BMG plate to artificially induce the precipitation of B2 crystals in the glassy matrix and then to tune mechanical properties. Through adjusting local melting process parameters (i.e. input powers, local melting positions, and distances between the electrode and amorphous plate), the size, volume fraction, and distribution of B2 crystals were well tailored and the corresponding formation mechanism was clearly clarified. The resultant BMG composites exhibit large compressive plasticity and high strength together with obvious work-hardening ability. This compelling approach could be of great significance for the steady development of metastable CuZr-based alloys with excellent mechanical properties.

Martensitic Transformation and Plastic Deformation of TiCuNiZr-Based Bulk Metallic Glass Composites

“…Until now, no tensile ductility of TiCu-based BMG composites with precipitation of B2 crystals had been achieved in contrast to Ti-based BMG composites with a precipitation of ductile α-Ti or β-Ti dendrites in the glassy matrix [15,16,[30][31][32]55]. Based on previous results [15,16,[30][31][32]55], the tensile ductility of BMG composites strongly depended on the crystalline volume fraction, size, and distribution of crystals as well as on suitable glass-forming ability (GFA) [6,[13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Until now, several approaches were proposed to describe transformation toughening in BMG composites [42,56,57], among which the yield strength and fracture strain can be successfully described by a strength model considering both percolation and an empirical, three-microstructural-element-body approach, respectively.…”

“…The fracture morphologies (Figure 5f) show a number of vein-like and river-like patterns while some fine river-like patterns appear at the interface between the amorphous phase and the crystals, implying that the "blocking effect" [52] originating from the crystals has a large influence on the fracture mode. Generally speaking, by introducing ductile shape memory crystals into the glassy matrix, the ductility of BMG composites can be improved [20][21][22][23][24][25][26]. During the early stage of deformation, martensitic transformation occurs within B2 crystals in CuZr-based BMG composites [20][21][22][23][24][25][26].…”

“…Generally speaking, by introducing ductile shape memory crystals into the glassy matrix, the ductility of BMG composites can be improved [20][21][22][23][24][25][26]. During the early stage of deformation, martensitic transformation occurs within B2 crystals in CuZr-based BMG composites [20][21][22][23][24][25][26]. With increasingly applied stress, martensitic transformation becomes more prominent while a large amount of twins form easily within B2 crystals with a relatively lower stacking fault energy [53].…”

“…Based on the concept of transformation-induced plasticity (TRIP), CuZr-based BMG composites were developed by introducing the ductile, shape memory B2 CuZr phase into the glassy matrix [20][21][22][23][24][25][26]. Such BMG composites exhibit high strength and good plasticity together with obvious work-hardening under compressive and tensile loading conditions [20][21][22][23][24][25][26].…”

“…Based on the concept of transformation-induced plasticity (TRIP), CuZr-based BMG composites were developed by introducing the ductile, shape memory B2 CuZr phase into the glassy matrix [20][21][22][23][24][25][26]. Such BMG composites exhibit high strength and good plasticity together with obvious work-hardening under compressive and tensile loading conditions [20][21][22][23][24][25][26]. In order to promote the further development of such shape memory BMG composites, a lot of research has been devoted to applying this concept to other glass-forming compositions [27][28][29][30][31][32].…”