Effect of Nitrogen on Ni-Cr Alloys

Nitrogen as an alloying element in heat-resisting materials-I

Abstract

The effect of nitrogen on nichrome and Nimonic alloys were investigated. These alloys were prepared in the following manners by using raw metals of high purity by melting rapidly in a Tammann furnace: (a) melted in air, (b) melted in air and added nitrogen in the form of nitrided chromium.
The nitrogen content of all alloys melted in air was in the range of 0.03-0.04%N. Che-mical analyses of these alloys showed large amount of "soluble" nitrogen (soluble in hydro-chloric acid: water=1:1) in nichrome and of "insoluble" nitrogen (insoluble in hydrochloric acid but soluble in fuming sulphuric acid) in Nimonic alloys. Hence, nitrogen in the former was presumed to be contained as solid solution, and that in the latter as both aluminium nitride and titanium nitride.
Small amount of nitrogen in Nichrome modified various properties a little: it strengthened the material without decreasing the ductility so much, increased the electrical resistance, decreased a temperature coefficient and increased the expansion