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Stehr, G.: Material Science for Engineers page 1 Chapter 6: Phase Diagrams Equilibrium Microstructural Development
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Stehr, G.: Material Science for Engineers page 2 BMW light metal foundry , manufacturing aluminum crankcase for the 6 - cylinder diesel engine Preparation of the anorganic sand core
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Stehr, G.: Material Science for Engineers page 3 Filling process with the liquid metal BMW light metal foundry , manufacturing aluminum crankcase for the 6 - cylinder diesel engine
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Stehr, G.: Material Science for Engineers page 4 Crankcase for the BMW engine BMW light metal foundry , manufacturing aluminum crankcase for the 6 - cylinder diesel engine
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Stehr, G.: Material Science for Engineers page 5 Introduction 1. Phase diagram : What microstructure should exist at a given temperature for a given material composition? 2. In next chapters: heat treatment How fast will the microstructure form at a given temperature? What temperature versus time history will result in an optimal microstructure? 3. Phase rule : number of microscopic phases at a given state condition (set of values for temperature, pressure, other variables…) 4. Lever rule ( Hebelgesetz ) to quantify our interpretation of the phase diagrams (composition and amount of each phase ) 5. Fe-Fe 3 C diagram the most important foundation for the steel industry
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Stehr, G.: Material Science for Engineers page 6 Terms and definitions (part 1/4) Phase : a chemically and structurally homogeneous portion of the microstructure Component : a distinct ( eigenständig ) chemical substance from which the phase is formed Example 1: Solid solution of copper and nickel Cu and Ni are so similar in nature, that they are completely soluble in each other in any alloy proportions. This is a single-phase-system (one solid solution) with two components (Cu and Ni). Example 2: Solid solution of MgO and NiO For materials systems involving compounds rather than elements, the compounds can be components. This is a single-phase-system (one solid solution) with two components (the compounds MgO and NiO).
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Stehr, G.: Material Science for Engineers page 7 Single-phase microstructure of commercially pure molybdenum, 200 × . Although there are many grains in this microstructure, each grain has the same uniform composition . Polycrystaline structure, each crystal grain differs only in the crystalline orientation, not in the chemical composition. (From ASM Handbook, Vol. 9: Metallography and Microstructures, ASM International, Materials Park, OH, 2004.)
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Stehr, G.: Material Science for Engineers page 8 Terms and definitions (part 2/4) As pointed out in a previous chapter, solid solubility is limited for many material systems.
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