Studies of Ti 1.5Zr 5.5V 0.5(M xNi 1− x) 9.5 (M = Cr, Mn, Fe, Co, Cu, Al): Part 1. Structural characteristics

Abstract

In Part 1 of this two part series of papers, the structural characteristics of quinary alloys Ti 1.5Zr 5.5V 0.5(M x Ni 1− x ) 9.5 with M = Cr, Mn, Fe, Co, Cu, or Al and x = 0.1 or 0.2 are reported. All 12 alloys are composed of Laves phases (C14 or C15) and non-Laves Zr–Ni phases. Only partial Cu-substitution retains a Zr 7Ni 10-dominated microstructure. Substitutions of elements with fewer outer shell electrons, such as Al, Mn, and Cr, were found to promote more C14 phase while Fe- and Co-substitutions favored the C15 structure. Average electron density was found to have a determining role in the predilection toward C14/C15 phases. As the Ni-content in the alloy decreases, the structure of non-Laves phase changes from Zr 7Ni 10 to Zr 7Ni 10 + Zr 9Ni 11, then to Zr 9Ni 11, and finally to Zr 9Ni 11 + ZrNi. The solubilities of V and Cr in the Zr 7Ni 10 and Zr 9Ni 11 phases are very low and the contents of other substitutional elements in these phases are lower than in the Laves phases.