Plasticity-improved Zr–Cu–Al bulk metallic glass matrix composites containing martensite phase

Abstract

Zr 48.5 Cu 46.5 Al 5 bulk metallic glass matrix composites with diameters of 3 and 4 mm were produced through water-cooled copper mold casting. Micrometer-sized bcc based B2 structured CuZr phase containing martensite plate, together with some densely distributed nanocrystalline Zr 2 Cu and plate-like Cu 10 Zr 7 compound, was found embedded in a glassy matrix. The microstructure formation strongly depends on the composition and cooling rate. Room temperature compression tests reveal significant strain hardening and plastic strains of 7.7% and 6.4% before failure are obtained for the 3-mm-and 4-mm-diam samples, respectively. The formation of the martensite phase is proposed to contribute to the strain hardening and plastic deformation of the materials.

Microstructure and mechanical properties of slowly cooled Cu47.5Zr47.5Al5

“…38 The formation of the CuZr martensite phase has already been reported for Cu 50 Zr 50 and in a Cu-Zr-Al alloy. 39,40 In contrast, the middle and bottom sections of the 5-mm-diameter rod show very similar XRD pattern as the 2-and 3-mmdiameter rods. Figure 3 displays the DSC scans for the differently solidified samples.…”

Deformation-Induced Martensitic Transformation in Cu-Zr-Zn Bulk Metallic Glass Composites

“…For example, CuZr-based BMG composites with different sample sizes containing minor element additions such as Al, Ti, Ag, Ni, Co, Y, Er, V, W, or Ta have been successfully fabricated [20][21][22][23][24][25][29][30][31][32][33][34][35][36][37]. Two key requirements should be satisfied for the fabrication of CuZr-based BMG composites: (1) maintaining sufficiently high glass-forming ability (GFA) in order to fabricate large-sized BMG composites [20][21][22][23][24][25][29][30][31][32][33][34][35][36][37]; and (2) stabilization of metastable B2 CuZr phase in order to suppress its decomposition into equilibrium phases (EPs) [29][30][31][32][33][34]. Previous results [22,38] demonstrated that minor Co addition to CuZr alloys can dramatically enhance the thermal stability of the B2 CuZr phase but gravely deteriorate the GFA of CuZr-based alloys.…”

Relationship between composite structures and compressive properties in CuZr-based bulk metallic glass system

“…However, these types of BMG composites still show the strain-softening behavior [9,10]. Recently, the concept of transformationinduced plasticity (TRIP) was applied into the (Cu 0.5 Zr 0.5 ) 100x Al x (x = 1, 2……10 at%) BMG system and both tensile ductility and work-hardening capability were obtained [11][12][13][14][15]. The martensitic transformation of the B2-CuZr phase was found to be responsible for the enhanced tensile properties [14,15].…”