Question 1 Briefly explain why, upon solidification, an alloy of eutectic compos

Question

Question 1 Briefly explain why, upon solidification, an alloy of eutectic composition forms a micro- structure consisting of alternating layers of two solid phases. Question 2: A 1.5 kg specimen of a 10 wt% tin-90 wt% lead is heated to 250°C; at this temperature it is entirely an -phase solution. The alloy is to be melted to the extent that 50% of the spec- imen is liquid; the remainder being the a-phase. This may be accomplished by either heat- ing the alloy or changing its composition while holding the temperature constant. a. To what temperature must the specimen be heated? b. How much tin must be added to the 1.5 kg specimen at 250°C to achieve this state? Question 3: A 65wt% Ni-35 wt% Cu alloy is heated to a temperature within the a-liquid phase region. If the composition of the ?-phase is 70 wt% Ni, determine the temperature of the alloy, the composition of the liquid phase, and the mass fraction of both phases

Explanation / Answer

1) when the composition is in molten state ,the redistribution the constituents take place.

This allows constituents to mix up and get distributed through out.

So when solidification starts, it starts at different nucleation sites throughput the mixture , then as solidification proceeds they gets added up alfa upon alfa and beta upon beta.

This process continues till the solidification ends. And that's why they layers of alfa and beta appears after solidification.

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