Crystal structure of Ni<inf>3</inf>Al with and without rare-earth additions at high temperatures

Crystal structure of Ni3Al with and without rare-earth additions at high temperatures Conference

Raju, SV, Godwal, BK, Durygin, A et al. (2014). Crystal structure of Ni3Al with and without rare-earth additions at high temperatures .

In-situ powder x-ray diffraction studies were carried out on melt quenched and directionally solidified Ni-Al-Cr and Ni-Al-Ce systems at high temperatures. The results indicate that, Ni-Al-Ce alloy undergoes structural distortion to D023 type structure between 600 and 700°C whereas, Ni-Al-Ce system shows clear evidences of presence of both L12 type phase and tetragonal distortion on the disordered phase starting from ambient conditions. Thermal expansion coefficients are found to be 2×10-5 K-1 and 2.642×10-5 K-1 for Ni-Al-Cr and Ni-Al-Ce systems. Segregation of Ce at the grain boundaries is found to improve the phase stability of the ordered L12 structure at high temperatures. Further, we have compared the results to that of undoped parent and the details are discussed in connection with strength.