enmaexam1a - Mechanical Tm = E = CTE = Density More steeper...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Mechanical Tm = E = CTE = Density More steeper for atoms that have higher Tm – Properties related to carrying load safely – Elastic modulus (E) • Measures stiffness, Based on atomic bond strength and crystal structure – Strength (σy) • Measures resistance to permanent deformation • Based on defect concentration, grain structure, and phases – Fracture Toughness (KIC) • Resistance of materials to cracking and fracture • Based on phases and macro-defects Fatigue resistance (Cycles to failure) – • Resistance of materials to failure under repeated cyclic load • Based on grain structure and macro-defects – Hardness • Resistance of materials to localized plastic deformation • Based on defect concentration, grain structure, and phases Thermal – Properties related to material changes with temperature – Coefficient of Thermal Expansion (αCTE) • Measures the rate at which materials expand with increased temperature • Based on atomic bond strength and crystal structure – Thermal Conductivity (κ) • Measures rate at which heat is transferred by conduction • Based on bond type, crystal structure, and phases – Heat Capacity (Cp) • Measures the amount of heat needed to raise a material’s temperature by 1°C. • Based on bond type, crystal structure, and phases – Thermal diffusivity ( a ) • Measures the speed at which a material heats. Proportional to αCTE/Cp • Based on bond type, crystal structure, and phases Metals • Moderately high stiffness (E) • Moderately high strength (σys) – Can be enhanced by alloying – Can be enhanced by processing • Mechanical work • Heat treatment • High ductility - easy to deform • High toughness (KIC) - resistant to fracture • Low electrical resistivity (ρ ) • High thermal conductivity (κ) • High optical reflectivity – shiny surface • High reactivity – poor corrosion resistance Ceramics (Crystalline and Amorphous) • Non-metallic, inorganic solids • High stiffness (E) • High strength (σys) • High hardness • High wear/abrasion resistance • High temperature stability (crystalline) – Low reactivity – resistant to corrosion/oxidation – Resistant to creep/stress relaxation • High electrical resistivity (ρe) • Moderate to high thermal conductivity (κ) (crystalline) • Low ductility – difficult to form • Low fracture toughness (KIC) – Low tolerance for stress concentrations/defects/flaws
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/02/2011 for the course ENMA 300 taught by Professor Alsheikhly during the Spring '11 term at University of Maryland Baltimore.

Ask a homework question - tutors are online