phase rule.pptx

Phase rule

1. LEAD –SILVER SYSTEM Lead-silver system is an example of two component system. Components are completely miscible with each other and do not form any chemical compound. Phase diagram of pb -Ag system show that composition of Ag plotted on the x-axis corresponds to its composition in the liquid melt. Phase rule

2. - - - - - - - - - - - - - - - - - - - - - - - - . Liquid melt B Y X Z 961 Ag +melt Solid Ag+eutectic Solidpb + eutectic C E T A G 327 303 Pb + melt 100% 0% 2.6% Composition( wt%ag ) Temperature C o F

3. Phase diagram of Pb -Ag system : 1 . A&B show melting &freezing point of pure Pb (327)&Ag(961) respectively curves: 1.curveAE:Represent a freezing point of lead in presence of liquid melt, ↔ solid pb Liquid melt 2.curveBE:Represent the freezing point of Ag in the presence of liquid melt ↔ solidAg Liquid melt According to condenced phase rule: F=C-P+1 F=2-2+1 F=1 Univariant

4. 3 .point.E is called as EUTECTIC POINT .at E three phases are co-exist ,the phases are solid pb,solid Ag, liquid melt. F=C-P+1=2-3+1=0 PointE is univariant 4.AREAS: 1.lineCED :area below CE consist of solid pb and eutectic and area below ED consist of solid Ag and eutectic F=C-P+1 =2-2+1=1 so system is univariant 5.AREAS AEC &BED : In Area AEC pure Pb is in equilibrium with liquid melt In areaBED pureAg is in equilibrium with liquid melt F=C-P+1=2-2+1=1 so sysytem is univariant

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