Thermo-mechanical stability of bulk (Al1–xCrx)2O3 solid solution

Abstract Bulk α–(Al,Cr)2O3 (where, x = 0, 0.1, 0.3, 0.5) sintered compacts were obtained at 1600–1700 °C, whose thermo-mechanical behavior were observed upon reheating at 25–1200 °C. Unlike bulk α–Al2O3 sintered samples, all the bulk α–(Al,Cr)2O3 sintered compacts showed a noticeable unusual flexural strength reduction at 600 °C. However, thermal shock behavior of all the α–(Al1–xCrx)2O3 samples (sintered at 1650 °C) exhibited a similar trend with retention of 33–38% of initial strength after the 12th cycle. Selected sintered α–(Al0.5Cr0.5)2O3 samples were reheated and quenched to observe any changes (phase, structural) using XRD, XPS, and FT-IR. The phase and binding energy did not reveal any change. The characteristics bands of MO6 units exhibited a lowering of wavelength by ∼2.5 cm−1 (original peaks at ∼592 and ∼648 cm−1) when reheated for 1 h and quenched from 600 °C. But, on prolonging the reheating time at 600 °C for 2 and 6 h, the band position shifted back to its original place. The force constant and bond energy are plausibly responsible for the fluctuational of molecular vibration to reach a time-dependent thermal equilibrium, particularly at ∼600 °C in case of α–(Al,Cr)2O3.