First order transitions:variation of equilibrium S.J.T.U. pressure with temperature(2) Phase Transformation and Applications dG=dGB Pand Talong this line =-V B T Figure 4.4 Pressure-temperature relationship First-order transition for equilibrium between phases A and B. The first derivatives are discontinuous at G-T Second-order transition The first derivative may be continuous and the second derivatives are discontinuous SJTU Thermodynamics of Materials Spring2007©X.J.Jin Lecture 7 equilibrium IPhase Transformation and Applications S. J. T. U. SJTU Thermodynamics of Materials Spring 2007 © X. J. Jin Lecture 7 equilibrium I First order transitions: variation of equilibrium pressure with temperature (2) A = dGdG B S T G p ⎟ −= ⎠⎞ ⎜⎝⎛ ∂∂ V pG T −= ⎟⎟⎠⎞ ⎜⎜⎝⎛ ∂∂ First-order transition The first derivatives are discontinuous at G-T Second-order transition The first derivative may be continuous and the second derivatives are discontinuous