The thermal and electrical conductivities of zirconium and of some zirconium alloys

Abstract

Three samples of zirconium and nine zirconium alloys have been studied, six with tin contents ranging from 0.84–6.7 wt. %, and alloys with 1.48% aluminium, 7.6% molybdenum and 9.79% niobium. The thermal conductivity of zirconium has been measured to 780°C and the electrical resistivity to 970°C. The Lorenz function is found to decrease from about 3.10·10 −8 to 2.63·10 −8 J ohm/sec °C °Abs. over the range 50–750°C. For these alloys the thermal conductivity determinations were mainly restricted to the range 50–250°C, and the electrical resistivity determinations mainly covered the range 20–600°C. Higher temperatures were reached in a few cases and the molybdenum and niobium alloys were found, to undergo considerable changes in both properties after heat treatment, presumably due to the occurrence of phase changes when held at temperatures above 400°C. In two instances, for a 1.65% tin alloy and the heat-treated niobium alloy the thermal conductivity determinations were extended to over 600°C. Using the values at 50°, 150° and 250°C the line K = 2.503·10 −8 T ρ + 0.0223 is obtained from a plot of thermal conductivity, K, expressed in J cm/cm 2 sec °C, against absolute temperature, T, divided by electrical resistivity, ρ, ohm cm 2/cm. All points are within 11% of this line and all but three within 5%. Results of other workers are discussed and examined in a similar way.