Conventional transmission electron microscopy is employed to investigate in situ electron-beam-induced phase transformations in vacuum-deposited amorphous aluminum fluoride (a-AlF3) self-developing thin-film resists. The a-AlF3 resists exhibit a very complex sequence of crystallization transitions with three crystalline materials (Al, AlF3, and Al2O3) formed sequentially as the electron dose increases from 10(5) to 10(7) Cm-2. Thermally evaporated "dry" a-AlF3 is dissociated into Al crystalline colloids at a threshold dose of similar to1 x 10(5) Cm-2, and begins to transform into crystalline AlF3 (c-AlF3) at a dose of similar to1 x 10(6) Cm-2. However, water contained in the "wet" films accelerates the transition of a-AlF3 to c-AlF3 at a reduced threshold dose of similar to2 x 10(5) Cm-2. Moreover, a-AlF3 films prepared by electron-beam deposition require a markedly different dose for each substance to crystallize, attributed to a microstructure variation. For all of the a-AlF3 films, textured Al2O3 is formed at doses of greater than or equal to 1 x 10(7) Cm-2, also with the aid of H2O absorbed from the microscope vacuum and by the following chemical reaction: 2AlF(3(s)) + 3H(2)O((g)) --> Al2O3(s) + 6HF((g)).