PHASE RELATIONSHIPS IN TANTALUM-RICH TANTALUM-RUTHENIUM ALLOYS AT 1500 C. Period covered: May 1960 to November 1960

Arc-melted and homogenized alloys of tantalum and ruthenium containing 10, 20, 30, 40, 45, and 50 at.% ruthenium were heat-treated for 168 hours at 1500 deg C and quenched. Structure and lattice parameters of the alloys were determined by x ray powder photographs. Solubility of ruthenium in tantalum at 1500 deg C lies between 20 and 30 at.%. An intermediate phase having the stoichiometric composition TaRu exists from 20 to 30 at.% ruthenium to 48 plus or minus 2 at.%. Room temperature structure of TaRu is based on CsCl (Type B2) at 30% ruthenium composition, but distorted CsCl at the 40 and 45 at.% compositions. Complete x ray data for all alloys are presented. (auth)