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Principles For Understanding Heat Treating Materials: The Ellingham Diagram (Part 1)

Principles for Understanding Heat Treating Materials: The Ellingham Diagram (Part 1)

by Mike Powers, F.A.S.M.   In the previous article of this series, we investigated the wetting of solids by liquids in terms of the Young Equation.  Now we turn to one of the most utilitarian tools in thermodynamics and materials processing, the Ellingham diagram.  I feel it is only fair to start off with a brief discussion about the man behind the diagram.  Harry Ellingham was a British physical chemist, best known for his Ellingham diagrams, which summarize the empirically…

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Principles For Understanding Heat Treating Materials: The Young Equation

Principles for Understanding Heat Treating Materials: The Young Equation

Mike Powers, F.A.S.M. In the first two articles of this series we explored basic definitions and concepts associated with thermodynamic systems and investigated the Laws of Thermodynamics and their implications for process spontaneity, process irreversibility and the importance of the Gibbs free energy.  Now we move on to understanding the principles of the Young Equation and how it describes wetting of solids by liquids. I would like to start off with a brief eulogy to Thomas Young (Fig. 1), a…

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Principles For Understanding Heat Treating Materials: Thermodynamics (Part 2)

Principles for Understanding Heat Treating Materials: Thermodynamics (Part 2)

by Mike Powers, F.A.S.M. In part 1 of this article we explored the definition of a thermodynamic system, the transfer of matter and energy across system boundaries, what is meant by system equilibrium, the definition of state functions, and the modes of energy transfer as expressed by work and heat.  In part 2 we will investigate the Laws of Thermodynamics and their implications for process spontaneity, process irreversibility and the importance of the Gibbs free energy. For our purposes, we…

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Principles For Understanding Heat Treating Materials: Thermodynamics (Part 1)

Principles for Understanding Heat Treating Materials: Thermodynamics (Part 1)

by Mike Powers, F.A.S.M. This is the first in a series of articles addressing traditional and contemporary methods for heat treating and brazing of advanced engineering materials.  The objective is to emphasize the basic thermodynamic principles underlying practical applications in materials processing.  To that end, I will begin with a presentation of some important thermodynamic concepts. Traditionally, the branch of physical science known as chemical thermodynamics is generally viewed as distinctly dry and boring.  However, I am not one who…

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Predicting Size Change from Heat Treatment

While a precise forecast of a part's size change during heat treating cannot be expected, by considering potential factors, a heat treater can provide a reasonable estimate that can help the shop prepare for final machining operations....
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