Comparison of bulk metallic glass formation between Cu-Hf binary and Cu-Hf-Al ternary alloys

Abstract

Optimized compositions for bulk metallic glass (BMG) formation have been determined for the CuÀHf binary and CuÀHfÀAl ternary systems. The CuÀHfÀAl BMG-forming composition region is identified to correlate with the (L ! Cu 10 Hf 7 + CuHf 2 + CuHfAl) eutectic reaction. The eutectic temperature is reduced by nearly 50 K relative to that of the binary eutectic, demonstrating the significant role of the third element Al in stabilizing the liquid. The fragility parameter D* of the Cu 55 Hf 45 binary and Cu 49 Hf 42 Al 9 ternary supercooled liquid was determined from relaxation time measurements, indicating that Al incorporation also leads to a "stronger" liquid. The combination of these thermodynamic and kinetic effects is responsible for the dramatic enhancement of glass-forming ability from the CuÀHf binary to the CuÀHfÀAl ternary.

Rapid chemical and topological ordering in supercooled liquid Cu46Zr54

“…Binary transition metal (TM) bulk metallic glasses (BMGs), however, do not form easily. They have (thus far) been reported in Cu-Zr [6][7][8][9], CuHf [10], Ni-Nb [11], and Ni-Ta [12] alloys. The Cu-Zr metallic glasses are particularly interesting since they form BMGs at several specific concentrations over a wide composition range (30 -60 at.% Zr) [8][9] and have been extensively studied.…”

Investigations of compressive strength on Cu-Hf-Al bulk metallic glasses: Compositional dependence of malleability and Weibull statistics

“…The detail can be found in the Ref. [27]. For these samples, their monolithic glassy structures are confirmed by XRD and TEM techniques taken from the cross-sectional surfaces of the as-cast rods with their corresponding D c .…”

“…1(a) shows the BMG-forming composition zone (critical diameter, D c ! 2 mm) and the terminal compounds (CuHfAl, Cu 10 Hf 7 and CuHf 2 ) in competition with the glassy phase when cooling from the supercooled liquid in Cu-Hf-Al system [27]. The relatively wide BMG-forming zone offers a good range to investigate the compositional dependence on deformation behaviors.…”

“…In the first, we have investigated the compositional dependence of malleability under compression for ternary Cu-Hf-Al BMGs, in which a large glass-forming composition range and good malleability have been clarified [27,28]. In the second, the relationships among malleability, GFA and elastic constants have been examined.…”

Cu-Hf-Al amorphous/nanocrystalline composite particles produced by milling

“…Th e materials of bulk metallic glasses (BMG) attract tremendous attention because they off er unique mechanical properties such as ultrahigh strength or high hardness [1][2][3][4][5]. Copper-based amorphous alloys are particularly interesting for practical applications as new structural materials due to their signifi cant advantages, including their low cost, high fracture strength of around 2 GPa, oft en coexisting with visible ductility, and feasibility for the formation of BMG based composites [5][6][7][8][9][10].…”