Diagrama De Fases

Commentary

Phase Diagrams

Phase Diagrams of Important
Electronic Materials
C.R. Kao

A phase diagram is the most concise
representation of the phase equilibria
present in a system. Phasediagrams
a re i ndispensable i n understanding
phase transformations, solidification,
interfacial reactions, and the accompanying changes in microstructure.
Knowledge of the phase equilibria of amaterial system is, therefore, critical for
the improvement of existing materials
and the development of new materials.
M ore s ignificantly , with the rapid
development of thermodynamic modelingof phase diagrams, information that
can be obtained from phase diagrams is
no longer limited to the phase stability
o f a single phase or the chemical
(interfacial) stability between multiplephases. The driving forces for phase
transformations, chemical reactions,
a nd diffusion processes can now
be estimated quantitatively once the
proper thermodynamic modeling of a
materials systemhas been performed.
The knowledge of the driving forces
c an then be used to rationalize
o bserved p henomena, or even to
s erve as inputs of kinetic models
f or quantitative predictions. Withappropriate thermodynamic modeling,
even the metastable phase equilibria and
the driving forces involving metastable
phase(s) can be accurately calculated.
Thermodynamic modeling of phase
diagramsis also quite helpful in simplifying the time-consuming experimental
d etermination of phase diagrams.
Moreover, thermodynamic modeling
combined with kinetic modeling, such
as solidificationmodeling and diffusion
modeling, can significantly cut down the
development time of new products.
T he electronics industry faces
a ccelerating demands for products
with higher functionality andgreater
p ortability at lower prices. A t the
same time, environmental regulations
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demand the elimination of certain toxic
elements, such as lead, from electronic
products. Central to these...