Computational Thermodynamics and CALPHAD Basics
How Gibbs energy models, databases and phase-equilibrium calculations support alloy and process design.
The central idea
Computational thermodynamics represents the Gibbs energy of phases as functions of temperature, composition and pressure. Equilibrium follows from minimising total Gibbs energy.
Databases carry knowledge
CALPHAD databases combine assessed experimental and theoretical information across many systems. Their value depends on the phases, elements and composition range included.
What calculations provide
Equilibrium phase fractions, transformation temperatures, chemical potentials and driving forces support alloy design, heat treatment and process interpretation.
What equilibrium does not provide
CALPHAD alone does not predict transformation rate, morphology, segregation length scale or final grain size. Kinetic and process models are required for those questions.
Working rule
Check database scope and phase definitions before trusting a diagram. Computed precision is not the same as physical accuracy.