Transformation-induced plasticity in bulk metallic glass composites evidenced by in-situ neutron diffraction

Abstract

Transformation-induced plasticity in a strain-softening amorphous matrix consisting of austenite B2 was studied by in-situ neutron diffraction, coupled with molecular dynamic simulation. It was found that the martensitic transformation from B2 to B19' upon loading commenced at the macroscopic yielding which increased with the decrease of the fraction of the parent austenite B2 phase, and the threshold lattice strain for the martensitic transformation is almost the same in different samples, suggesting that the martensitic transformation in the current glassy matrix is strain-controlled. Analysis of load partition and strain accommodation unveiled that B2 has elastic anisotropy, and the desirable elastic match between B2 and the amorphous matrix ensures a good cooperative deformation. Additionally, molecular dynamic simulation revealed that atoms at the interface between B2 and the amorphous matrix deviated from the standard B2 lattices and acted as nucleation site for the martensitic transformation, eventually giving rise to the strain-controlled martensitic transformation. Our findings provide new insights into the mechanism of phase transformation-mediated plasticity at the microscopic level, and have useful implications for developing novel, high-performance bulk metallic glass composites.

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

“…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].…”

“…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].…”

Microstructural Evolution from Dendrites to Core-Shell Equiaxed Grain Morphology for CoCrFeNiVx High-Entropy Alloys in Metallic Casting Mold

“…The prepared alloy presents excellent mechanical properties even in cryogenic conditions. In addition, the transformation-induced plasticity (TRIP) effect, which has been developed to improve the plasticity of the steels, titanium alloys [25], and amorphous alloys [26], has also been successfully introduced into the Fe 50 Mn 30 Cr 10 Co 10 [27] and TaHfZrTi [28] HEAs.…”

The Microalloying Effect of Ce on the Mechanical Properties of Medium Entropy Bulk Metallic Glass Composites

“…However, a fatal drawback of BMGs, the limited ductility and strain softening as loading, restricts its application as an advanced structural material [3][4][5]. Recently, some alloy systems have offered the possibility to produce in situ composites consisting of shape memory crystals and a glassy matrix [6][7][8][9]. Bulk metallic glass composites (BMGCs) can overcome the problems with BMGs using a transformation induced plasticity (TRIP) effect as loading [10][11][12][13].…”