A grain boundary mobility discontinuity in reactive element Zr-doped Al2O3

A grain growth study on polycrystalline 180 wt. ppm Zr-doped Al2O3 has revealed a discontinuous increase in grain boundary mobility. The mobility increases by over an order of magnitude within a narrow temperature window between 1550 and 1650 °C. The discontinuity is attributed to a grain boundary complexion transition that occurs at about 1600 °C. This grain boundary complexion transition has important implications for creep and oxidation protection, and technological issues such as scale growth in high-temperature alloys.