... grain boundaries would be expected to have little effect on the diffusivity of aluminum. 10 -9 10 -12 10 -11 10 -10 10-5 10 -3 10 -1 10 1 10 3 10 7 10 -7 10 5n=3/16n=-1/6 10 -9Po2 in ... 1124-1130. Mass Transfer in Multiphase Systems and its Applications 388 Engineering with Membranes, Vol I, paper No. PA.4-17, p313, June 3-6, 2001, Granada, Spain. Siebold, M.; Frieling, P. ... occurs at grain boundaries. Assuming that te’ = 1 and OgbD >> lgAbD , and inserting ZO = -2 and Eq. (6) into Eq. (4) gives Control of Polymorphism and Mass- transfer in Al2O3...