Studies of Ti1.5Zr5.5V0.5(MxNi1−x)9.5 (M = Cr, Mn, Fe, Co, Cu, Al): Part 1. Structural characteristics

In Part 1 of this two part series of papers, the structural characteristics of quinary alloys Ti1.5Zr5.5V0.5(MxNi1−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 Zr7Ni10-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 Zr7Ni10 to Zr7Ni10 + Zr9Ni11, then to Zr9Ni11, and finally to Zr9Ni11 + ZrNi. The solubilities of V and Cr in the Zr7Ni10 and Zr9Ni11 phases are very low and the contents of other substitutional elements in these phases are lower than in the Laves phases.