Introdution to metals and alloys: classification of the main metallic alloys. Understanding about metallic microstructures and the main degradation modes observed in metallic objects.
Rui Jorge Cordeiro Silva
Weekly - 5
Total - 108
Basic knowledges of chemistry (acid-base and redox reactions) and crystallography.
- Microestruturas - Notas para apoio à disciplina de Materiais Metálicos, elaboradas por Rui Silva (docente da disciplina), 2010.
- Corrosão - Notas para apoio à disciplina de Materiais Metálicos, elaboradas por Rui Silva (docente da disciplina), 2010.
- Introdução à Metalurgia, Alan H. Cotrell, Ed. Gulbenkian, 1975.
- Phase Transformations in Metals and Alloys, David A. Porter e K. E. Easterling, Van Nostrand Reihold (UK), 1984.
- Princípios de Ciência e Engenharia dos Materiais, Willian F. Smith, Mc-Graw-Hill de Portugal, 1988.
- Metallography and Microstructure of Ancient and Historic Metals, David A. Scott, Getty C. I., 1991.
- A Seach for Structure - Selected Essays on Science, Art, and History, Cyril Stanley Smith, MIT press, 1981.
- A history of Metallurgy, R.l F. Tylecote, The institute of Materials, 1977.
Documents for this course are available in Moodle plataform.
- The discipline has weekly theoretical lessons, theoretical-practical lessons or laboratories.
- Transparencies or PowerPoint presentation is used for theoretical classes being the matter exposed in a class room when required.
- The resolution of exercises is done during the theoretical-practical lessons in class room about the matter given during the theoretical classes. Laboratorial classes are related to the experiences demonstration of the concepts already given both in theoretical and problem sessions.
- The student''''''''''''''''''''''''''''''''s progress assessment consist of 5 components: 3 mini-tests and 2 lab group reports (avaliation type B, according to the FCT-UNL assessment rules).
- Course success requires an average positive grade (NR) in the 2 lab reports (R1 and R2):
NR=(R1+R2)/2 > 9.5
The students with an average grade in the three mini-tests, equal or superior to 9.5 in a ranking of 20 have exemption from final examination. The student needs to have in the first mini-test at least a grade of 6.0:
NT=(T1+T2+T3)/3 > 9.5 com T1,T2,T3> 6 in 20
Student success in course requires a final examination or a mini-tests average grades of at least 9.5 in a ranking of 20. The final grade will be a weighted average of the final exam grade or mini-tests average grade (75%) plus lab reports grade (25%):
NF=0.75 (NF or NE) + 0.25 NR > 9.5 (NT or NE)>9.5 e NR>9.5
Note: Assessment grades are in a range of 0 to 20 (100%).
Metals and alloys (basics)
The chemical bond characteristic of metals. Metallic crystals: most commons atomic arrangements in metals (body centred cubic, phase centred cubic and hexagonal close-packed structures) Monocrystalline and polycrystalline materials. Notion of grain and grain boundaries. The meaning of texture in polycrystalline metals. Main physical and mechanical properties of metals.
Definition of alloy and alloying elements. Binary, ternary and other alloys with more components. Notion of solid solution (substitutional and interstitial solid solutions). Monophasic and polyphasic alloys.
Archeometallurgy: the first metals ands alloys used by man. Native metals, such as such as gold, platinum, silver, or copper. The first alloys man made: arsenical coppers and the tin bronzes. Iron and ferrous alloys. Other metals with less expression in past.
Introduction to metallography. Metallic samples preparation (cutting, mounting, polishing and etching). Microstrutural observation (optical and electron microscopy observation) and interpretation of simple microstrutures. Examples.
Phase Equilibrium diagrams
Thermodynamics fundamentals needed for the comprehension of phase diagrams. The concept of a phase. Gibbs free energy and chemical potential. Thermodynamics equilibrium. The Gibbs’ Phase Rule. Application examples of the Phase Rule. Examples of phase diagrams for pure systems (systems p-T).
Binary diagrams representation. Chemical composition determination for biphasic regions. The triphasic equilibrium in binary alloys and the associated reactions (eutectic and peritetic type). Alloy composition, phase composition, crystallographic and microstrutural compositions differentiation. Determination of crystallographic compositions: The Lever Rule. Equilibrium microstructure prediction in the case of binary alloys. Case studies: Gold alloys (Au-Cu), silver alloys (Ag-Cu) and tin and brazing alloys (Sn-Pb)
Stable and metastable systems and other non-equilibrium microstructures. Coring and other compositional deviations. Case studies: steel and cast irons alloys (Fe-C), bronzes(Cu-Sn) and brasses (Cu-Zn).
Solidification and solid phase transformations
Study of metals solidification (nucleation and growth of pure metals). Alloys solidification: cellular and dendritic solidification. The constitutional supercooling. Microstructures from non-equilibrium cooling: coring, microsegregation and incomplete transformations. Compositional heterogeneities. Homogenisation heat treatment.
Pouring. As-cast structures and others microscopic and macroscopic heterogeneities in cast metal objects, such as porosities and inclusions. Some examples of as cast structures and solidification defects in ferrous alloys.
Solid state transformations. Favourable sites of nucleation. Diffusional and martensitic (diffusioneless) transformations in solids. Quenching in steels and other examples.
Main degradation modes in metallic materials
Corrosion. Dry and wet corrosion. Fundamental aspects of corrosion: electrochemical aspects (anodic and cathodic reactions, electrochemical potentials, galvanic series for metals and polarization), environmental parameters (relative humidity, oxygen potential, temperature, polluents, etç). Main corrosion forms. Pourbaix diagrams (corrosion, passivation and immunity regions). The importance of Pourbaix diagrams in choose the optimal preservation conditions in aqueous medium. Corrosion evolution and products. Case studies: rust in ferrous alloys, patinas formation in copper alloys and tarnisnhing in silver objects.
Other modes of degradation.
(This discipline has an internet page in Moodle: http://moodle.fct.unl.pt/)
Programs where the course is taught: