摘要
Sequential transformation in precipitate structure from L1 2 → B2-NiAl precipitate has been observed for Al 0.5 Co 1.5 CrFeNi 1.5 alloy with the increase in aging temperature. At 650 °C, the FCC matrix contained L1 2 precipitates (γ′), which were transformed into ordered B2 structure precipitate at 750 °C. A coarser and more stable B2-NiAl rich precipitate has been observed for higher aging temperature (850 °C). This transformation is attributed to the higher thermodynamic stability of B2-NiAl precipitates overcoming the nucleation barrier at higher temperatures.