Equilibrium high entropy phases in X-NbTaTiZr (X = Al,V,Cr and Sn) multiprincipal component alloys

X-NbTaTiZr, with X=Al,V,Cr and Sn, potential High Entropy Alloys obtained by arc melting were annealed to reveal the equilibrium constitution. AlNbTaTiZr and VNbTaTiZr alloys, made of two bcc solid solutions in the as-cast state, are composed of a bcc solid solution plus a minority phase, a Al–Zr intermetallic compound and a Zr–Ti hcp phase, respectively, while Cr and Sn containing alloys always present an intermetallic phase together with a bcc solid solution. Isochronal annealing on V- and Al- alloys revealed the mechanism of formation of the equilibrium microstructure.