Question

> Re 200 LL 2 TAB 97,4 loet 61.9 +B 577 o + 2 40 ce 92 wtf Sn Sn a. What is the composition (in terms of wt. % Sn) of the three phases that coexist in equilibrium at the eutectic composition and the eutectic temperature b. Give the weight fractions of a and B in the eutectic solid (from solidified liquid with a compositon of 61.9 weight percent Sn) at a temperature slightly below the eutectic temperature C. Sketch the microstructure of the hypereutectic Pb-Sn alloy at 80 weight percent Sn soon after reaching a temperature below the eutectic temperature 5

Answer 1

(61.9 %. In g At eutectic point eutectic, composition 38. 12Pb) and eutectic tempezabude circ? thaee phase that is a, ß and L co-exist in in 'equilibolum that at that point com position is Foom goupha Weight peacentage of sn -> -) 61.9% Twt Peocentage of sn. 61.9% 1 so A 5 weight fraction of Á and B It is simply find by the use of lever sule, ☺ weight fauction of a given by wa wtimesh at wty.snatk wt% sn at wtt.sn at p 97.5 - 61.9 97.5 19.2 Wa a 0.4547

(ii weight foaction of B is given by Wo at% sn at Q otni sincet R- utr sn at P ats. sn at P 61.9. 19.2 97.5 ~:192 WB30.5453 : fraction of x in eutectic Solid - 0.4547 foraction of B in eutectic solid : O. SAS3