The spectral emissivity at $\lambda =0.667\mathrm{}$ μ has been determined for an 18 percent W-Fe alloy and a 40 percent Fe-Co alloy. Changes have been detected at the peritectoid and peritectic reaction temperatures for W-Fe and at the $A_3$ point for Fe-Co. Emissivity changes found at 1044°K and 1292°K in Fe-Co are attributed to the order-disorder transition and the ferro to paramagnetic transformation, respectively. The resistivity of 40 percent Fe-Co has been determined as a function of temperature.

• Received 3 August 1948

DOI:https://doi.org/10.1103/PhysRev.74.1413