On the basis of the photomicrograph (i.e., the relative amounts of the microconstituents) for the lead?tin alloy shown in Figure and the Pb?Sn phase diagram (Figure), estimate the composition of the alloy, and then compare this estimate with the composition given in the figure legend of Figure. Make the following assumptions:?

(1) ? ? ??The area fraction of each phase and microconstituent in the photomicrograph is equal to its volume fraction;?

(2) ? ? ??The densities of the ? and ? phases as well as the eutectic structure are 11.2, 7.3, and 8.7 g/cm³, respectively; and?

(3) ? ? ? This photomicrograph represents the equilibrium microstructure at 180?C (355?F).

Transcribed Image Text:

Composition (at% Sn) 0. 20 40 60 80 100 327°C 600 300 Liquid 500 232°C a +L 200 8 +L 400 183°C 97.8 18.3 61.9 300 100 200 100 20 40 60 80 100 Composition (wt% Sn) (Pb) (Sn) Temperature ("C) Temperature (F)