Investigations in systems of tantalum base alloys with nitrogen

The spectral emissivity epsilonsub(lambda)(lambda = 650 nm) of Ta is decreased by the addition of 50 at.%Nb, 10 at.%W or 20 at.%Re at 1,500 (2,1000C). For the initial rate of nitrogen absorption by Ta and by the Ta-base alloys at 10-4 to 5 x 10-3 torr N2 and 1,650 to 1,9500C approximately v0 = k(T)psub(N2) is valid. The equilibrium nitrogen concentration in α(Ta,Nb,N), α(Ta,W,N) and α(Ta,Re,N) solid solutions at 1,600 to 2,0000C obeys the Sieverts' law and is decreased markedly at constant pressure and temperature when Ta is alloyed with W or Re. The reaction of nitrogen solution is exothermic, however, the heat of solution is less negative for alloys of Ta with W or Re than for Ta. The behavior of the entropy of solution is similar to that of the heat of solution. The results for the nitrogen solution in Ta base alloys are compared with the corresponding results for the nitrogen solution in Nb base alloys. (orig./GSC)