Influences of high temperature on the microstructural, electrical and mechanical properties of Ni-23 wt.% Al alloy

Karakose E., KESKİN M.

INTERNATIONAL JOURNAL OF MATERIALS RESEARCH, vol.106, no.1, pp.29-42, 2015 (SCI-Expanded) identifier identifier


The microstructural, electrical and mechanical characteristics of conventionally and rapidly solidified Ni-23 wt.% Al alloys after heat treatments were investigated. The microstructures of Ni-23Al alloys were examined by means of scanning electron microscopy and the phase composition was identified using X-ray diffraction analysis. The phase transitions during the solidification process were investigated using differential thermal analysis under an Ar atmosphere. X-ray diffraction analysis indicated that the Ni-23Al samples showed an intermetallic gamma'-Ni3Al phase, and we observed the intermetallic gamma'-Ni3Al phase together with the beta-NiAl phase after heat treatment at 700-900 degrees C for 24 h. We performed electrical resistivity measurements by using the four-point probe technique in the temperature range 100-900 degrees C. The resistivity of Ni-23 wt.% Al samples increases linearly with temperature. Vickers microindentation tests were carried out on the heat-treated samples with loads ranging from 392.26 mN to 1174.86 mN at room temperature. We found that the microhardness and effective elastic modulus values increased with increasing temperature and these values showed peak load dependence. The tensile and compressive stress values of the Ni-Al alloys also decreased with increasing temperature.