Electrical resistivity measurements in Ni–Cr alloys

The electrical resistivity measurements of Ni–Cr alloys were made as a function of temperature, Cr concentration and under different heat treatments. Solution heat treatments were performed at temperatures lying between 873 and 1273 K followed by quench in brine. Some samples were aged isochronally at temperatures in the range 423–923 K for 30 min and others aged isothermally at 673 K for various times. Isothermal ageing at 673 K shows a sudden rise in resistivity approaching a saturation value. The initial increase in resistivity during ageing may be ascribed by the gathering or clustering of Cr-atoms at early stages of precipitation as supported by X-ray diffraction data. The resistivity shows a continuous rise with increasing temperature as well as Cr-content. The anomalous resistivity behavior with rising temperature may be attributed to the CrNi3 ordering reaction.