MATS 3011 Lecture : Lecture 3242014.pdf
Document Summary
Suppose we have alloy w/ 35% ni wt% ni ---> Can find amt alpha w/ lever rule can find compositions of each phase w/ just tie line. To have eqbm condition, need to cool really slow. But usually don"t cool it slow enough to reach eqbm in reality --> rapid cooling. *using lever rule in above graph (in blue) -> results into a concentration gradient in liquid and solid(alpha) (both phases) We assume high enough diffusion w/in liquid phase & hence homogeneous composition of liq. Exterior is 35% ni inner has 46% ni outer has 31% ni. Exterior is 35% ni now solid comp. is avg btwn 46 and 35 inner has 46% ni outer has 31% ni. Exterior is what you predicted by tie line. -> avg composition is somewhere in between (it"s a weighted avg) (in blue) But for liquid, don"t have gradient, just use normal tie line procedure like you do for eqbm cooling.
