Phase relations and superconducting properties of YNi1-xCuxBC compounds

The effects of alloy composition, in particular with respect to Cu and B, o n the phase relations, the composition and the respective properties of YNi 1-xCuxBC superconducting compounds were studied. Parts of the Y-Ni-Cu-B-C p hase diagram were revealed, which are relevant for the formation of YNi1-xC uxBC. The peritectic solidification mode of the YNiBC compound could be dem onstrated, which also holds for the pseudoquaternary YNi1-xCuxBC phase. A m aximum Cu solubility of x approximate to 0.42 for YNi1-xCuxBC compounds was inferred from electron probe microanalyses of Y-Ni-Cu-B-C samples. The lat tice parameters (a, c) increase linearly with Cu content x. The boron conce ntration of the YNi1-xCuxByC phase may be varied within the Limits 0.93 < y < 1.12. The superconducting transition temperatures increase with both Cu and B content up to a maximum of T-c = 9.1 K. (C) 2001 Elsevier Science B.V . All rights reserved.