Effect of Cr Incorporation on the Mechanical Properties of HfMoTiZrCr, HfMoNbZrCr, and HfMoNbTiCr Refractory High-Entropy Alloys

Synergy of strength–ductility in HfMoTaTiZr refractory high entropy alloy through Cr addition

“…During deformation, the extension of cracks was impeded by the reticulated structure of the Laves phase, which decreases the quantity and size of cracks and was beneficial to the plasticity. The similar effect of a reticulated structure on the plasticity has been reported by Wang et al 28 …”

“…Together with the analysis results from XRD (Fig. 1) and the conclusion from previous work, 19,28,29,36–38 it is reasonable to conclude that the Laves phase should be (Cr, Mo) 2 (Hf, Ti, Zr). From Fig.…”

“…Laves phases with similar composition have also been observed in several Crcontaining RHEA. 28,[33][34][35] The diffraction peaks of the BCC phase shi to higher angles with Cr addition, indicating the d-spacings decrease, i.e., the lattice constant of HfMoTaTiZrCr 0.5 RHEAs is smaller than that of HfMoTaTiZrCr 0.5 because Cr has the smaller atomic radius than elements in HfMoTaTiZr. Thus, it is safe to conclude that a certain amount of Cr was dissolved in the BCC phase in HfMoTaTiZr and extra Cr reacted with HfMoTaTiZr to form the Laves phase.…”

“…Several previous studies have revealed that Cr alloying in bcc RHEAs may strengthen the alloys instead of degrading their good mechanical properties. [21][22][23][24][25][26][27] Wang et al 28 replaced Nb, Ti and Zr, respectively, with Cr and observed that a Laves phase emerged regardless of which element was substituted by Cr and a signicant enhancement in strength was achieved in all cases. Similar phenomena were also observed by Fazakas et al 29 (TiZrHfNbCr) and Yan et al 30 (WMoNbTiCr).…”