Abstract
? 2022 Elsevier B.V.We report the structural, mechanical and physical properties of the (MoReRu)(1?2x)∕3(PdPt)x and carbon-added (MoReRu)(1?2x)∕3(PdPt)xCy HEAs over wide ranges of x and y values. The former ones are found to crystallize in a hexagonal close-packed (hcp) structure for 0.042 ≤ x ≤ 0.167 and a face-centered cubic (fcc) structure for x = 0.333. For all the hcp compositions, a transformation to the fcc structure is induced by adding a certain range of carbon, whose width is narrowed with increasing x. Both the hcp (MoReRu)(1?2x)∕3(PdPt)x and transformed fcc (MoReRu)(1?2x)∕3(PdPt)xCy HEAs display superconductivity with Tc ranging from 1.75 to 8.17 K and mainly governed by the electron-phonon coupling strength. Furthermore, we show that the trends in Tc and microhardness of these HEAs correlate well the valence electron concentration (VEC), and that the structural transformation is likely due to the combined effects of VEC, lattice distortion and mixing entropy. Our results suggest that the structural transformation due to carbon addition is general for multicomponent alloys with an hcp structure.
NSTL
Elsevier