one hour then air cooled and heated at 200 f 93 3 c for 24 hours and then air cooled to room temperature the coefficient of thermal expansion for specimens of each heat were measured on a differential dilatometer from room temperature up to 95 c 203 f and from room temperature down to 120 c 184 f or to the m s temperature for each sample the samples were each measured differentially against a sample of fused silica glass nbs standard reference material no 739 which is known to have a coefficient of expansion of 0 45 u00d7 10 6 u00b0 c over the temperature range of interest the average coefficient of thermal expansion determined for each sample over the range 55 c to 90 c 67 f to 194 f is listed in table ii as well as the respective m s temperatures determined for the respective sample ______________________________________ avg coeff m sub s temp ex u00d7 10 sup 6 u00b0 c u00b0 c ______________________________________1 0 34 1032 0 21 1033 0 07 1064 0 01 lt 1205 0 33 lt 120______________________________________ the data of tables i and ii show the dramatic increase in the thermal expansion coefficient of the present alloy near the low and high ends of the claimed range for cobalt examples 6 10 were vacuum induction melted 300 pound experimental heats having compositions in weight.