9.3 Simple Eutectic Diagram S.J.T.U. Phase Transformation and Applications Page 6/30 A-B system,A and B are immiscible in the solid state,but completely miscible in the liquid state. When the melting point depression lines intersect,the material will solidify totally into m.B solid A and solid B,eutectic temperature. Liquid The lowest temperature at which a liquid solution of A and B may exist at equilibrium L+Solid B with solid A and B.eutectic composition. L+Solid A At eutectic point:phase rule TEutectic Liquid=solidA+solidB T Solid A+Solid B F=C-P+1=2-3+1=0 XEutectic A XB B If all three phases are present,at equilibrium, the system must at the eutectic temperature and the liquid will have the eutectic composition. Fig.9.5 Simple eutectic phase diagram. SJTU Thermodynamics of Materials Spring2007©X.J.Jin Lecture 16 Phase Diagram llPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2007 © X. J. Jin Lecture 16 Phase Diagram II Page 6/30 9.3 Simple Eutectic Diagram A-B system, A and B are immiscible in the solid state, but completely miscible in the liquid state. When the melting point depression lines intersect, the material will solidify totally into solid A and solid B, eutectic temperature. The lowest temperature at which a liquid solution of A and B may exist at equilibrium with solid A and B. eutectic composition. At eutectic point: / phase rule Liquid = solidA + solidB = − PCF =+ − + = 01321 If all three phases are present, at equilibrium, the system must at the eutectic temperature and the liquid will have the eutectic composition. TEutectic A B T xB Tm,A Tm,B Liquid L+Solid A L+Solid B Solid A + Solid B xEutectic Fig. 9.5 Simple eutectic phase diagram