The homogenized Al-Mg alloy is suddenly quenched and held isothermally:

Question

A) From 400C to 250C

B) From 400C to 200C

How long would it take to regrow an isolated particle of Al3Mg2 to a diameter of 15 microns, assuming that B(Beta) particles nucleate (t=0) from the matrix with an initial diameter of 10^-3 mikrometer, and that the diffusitivity at 250C and 200C is D=1x10^-11 cm^2/sec?

Please consider both cases of quenching at 250C and 200C, respectively.
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