1. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 The contents of this lecture are protected under U.S. copyright law and should not be duplicated or redistributed for commercial purposes. 1 MATSE 259 Lecture 3: Phase Diagrams and Deformation of Materials Christopher L. Muhlstein, Ph.D. Department of Materials Science and Engineering The Pennsylvania State University University Park, PA

2. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 2 Last Lecture Aluminum alloy designations Microstructures

3. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 3 Lecture 3: Key Concepts and References Reading binary phase diagrams Introduction to age hardening Elastic deformation of materials Reference: Callister, Chapter 9

4. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 4 Gibbs Phase Rule Relationship between components, phases, state variables, and degrees of freedom Gibbs phase rule P-T diagram for water Schaffer et al., The Science and Design of Engineering Materials (1999)

5. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 5 Phase Diagrams Binary phase diagram –phases present –composition of phases –relative amount of phases Solid solutions Callister, Materials Science and Engineering: An Introduction (2003)

6. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 6 Dispersion Strengthening and Precipitation Hardening Mechanism: small particles in a metal can impede deformation Dispersion strengthening –Particulates added to the (usually liquid) material –Material added should not react with base metal –Composite Precipitation Hardening –“Age hardening” –Particulates created in material by heat treatment –Nucleation and growth process –Phase diagram used to identify amenable alloy systems

7. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 7 Precipitation Hardening Phase diagram features –“Appreciable” solid solubility of one component –Solubility limit that decreases rapidly –Alloy composition less than solubility limit –Necessary, but not sufficient, condition for precipitation-hardenable alloy Hypothetical phase diagram of precipitation-hardenable alloy. Callister, Materials Science and Engineering: An Introduction (2003)

8. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 8 Precipitation Hardening Two-stage heat treatment –Solution heat treatment and quench –Precipitation heat treatment in  +  phase field (“aging”) Callister, Materials Science and Engineering: An Introduction (2003) Schematic of precipitation hardening heat treatment.

9. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 9 Precipitation Hardening Underaged Peak Aged Overaged Aging behavior of a hypothetical aluminum alloy. Callister, Materials Science and Engineering: An Introduction (2003)

10. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 10 Heat Treatment of Aluminum Alloys Under, peak, and overaged aluminum alloys Precipitation hardened 7150-T651 alloy. Callister, Materials Science and Engineering: An Introduction (2003)

11. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 11 Linear Elastic Behavior of Materials Engineering stress, , and strain,  Hooke’s law Poisson’s Ratio, Stiffness and compliance Schematic of tensile, shear, and torsion in elastic solids. Callister, Materials Science and Engineering: An Introduction (2003)

12. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 12 Measuring Tensile Behavior Schematic of tensile test.Schematic of tensile specimen. Specimen geometry Experimental setup ASTM Standards E8 and E9 Callister, Materials Science and Engineering: An Introduction (2003)

13. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 13 Room Temperature Elastic Moduli of Materials Compare –Polymers –Metals –Ceramics Ashby, Materials Selection in Mechanical Design (1999) A material property chart of Young’s modulus and density.

14. MATSE 259 Spring 2007, C. Muhlstein© C. Muhlstein, 2007 14 Elastic Behavior of Al, Fe, and Ti Alloys AlloyYoung’s Modulus, E (GPa) Poisson’s Ratio, v Al690.33 Ti1070.34 Steel2070.30 Room temperature behavior Elevated temperature behavior Temperature dependence of elastic modulus of metals. Callister, Materials Science and Engineering: An Introduction (2003) Room temperature elastic properties.