high grain boundary energy, locally high grain boundary mobility, favourable texture or lower local second-phase particle density. Factors hindering growth If there are additional factors preventing boundary movement, such as Zener pinning by particles, then the grain size may be restricted to a much lower value than might otherwise be expected. This is an important industrial mechanism in preventing the softening of materials at high temperature. Inhibition Certain materials especially refractories which are processed at high temperatures end up with excessively large grain size and poor mechanical properties at room temperature. To mitigate this problem in a common sintering procedure, a variety of dopants are often used to inhibit grain growth. References F. J. Humphreys and M. Hatherly (1995); Recrystallization and related annealing phenomena, Elsevier Materials science Metallurgy