Superplasticity in Pd40Ni40P20 metallic glass

A thermoplastic forming map of a Zr-based bulk metallic glass

“…shear transformation zones), and facilitates the formability. The similar effect of temperature on formability was also found in previous work [48][49][50][51]53]. However, when the strain rate keeps increasing, the strain rate sensitivity of FVC appears again, resulting in a transition from temporal homogeneity to inhomogeneity.…”

“…However, for a BMG with a certain composition, viscosity shows sensitivity to both temperature and strain rate. These temperature and strain rate parameters usually induce a transition from Newtonian to non-Newtonian flow within the homogeneous regime in SCLR, and affect the formability of BMGs [4,48]. These characteristics can be captured well by a phenomenological viscosity law proposed by Johnson et al [56] based on the free volume model of Cohen and Grest (the CG model) [57], in which the viscosity of the BMG in the TPF process is illustrated by [56] gð_ e; T Þ ¼ g 0 Dð_ e; T Þ exp a t T ð4Þ .…”

“…Whereas the decrease in viscosity with increasing strain rate at a certain temperature inherently induces a transition from Newtonian to non-Newtonian flow, this makes TPF much more difficult, and causes contradictory results. For instance, this transition was found to result in a dramatic decrease in tensile extensibility in a Pd-based BMG [48]. In particular, it was reported that Newtonian flow corresponding to significant structural rearrangement during TPF assists viscous flow with less thermal dissipation, and enhances the high-temperature formability of BMGs [49][50][51][52].…”

“…In particular, it was reported that Newtonian flow corresponding to significant structural rearrangement during TPF assists viscous flow with less thermal dissipation, and enhances the high-temperature formability of BMGs [49][50][51][52]. Accordingly, the exact relationship between the formability and the flow characteristic of BMGs during TPF is still unclear [4,[48][49][50]53]. One main reason for this is that no TPF map of a BMG has been constructed experimentally yet, unlike deformation maps.…”

Oxidation Behavior of a Pd43Cu27Ni10P20 Bulk Metallic Glass and Foam in Dry Air

“…It was reported that, upon relaxation at a temperature near T g , this ternary alloy could be easily deformed with an excellent superplasticity of 1260 pct, which made it possible to form complex shapes for industrial applications. [3] Most recently, the quaternary version of this family, the Pd-Cu-Ni-P glassy alloy, has been extensively studied, and the results indicated that the critical cooling rates to retain the glassy structure were significantly lower than those of the ternary alloy. [4][5][6] In addition, it was also found that the quaternary amorphous alloy containing certain amounts of porosity (i.e., metallic glass foam) exhibited interesting mechanical properties.…”