材料科學與工程基礎1(存儲版)
【正文】 a “ smart material” ? outline ? What is Materials Science and Engineering? ? Classification of Materials ? Environmental and Other Effects ? Materials Design and Selection 11 What is Materials Science and Engineering? ? 1. Definition Materials Science and Engineering (MSE) is an interdisciplinary field concerned with inventing new materials and improving previously known materials by developing a deeper understanding of the microstructurepositionsynthesisprocessing relationship. ▲ The term Composition Means the chemical makeup of a material ▲ Structure A description of the arrangement of atoms , as seen at different levels of detail. ▲ Synthesis Refers to how materials are made from naturally occuring or manmade chemicals. ▲ Processing Means how materials are shaped into useful ponents to cause changes in the properties of different materials. Figure Application of the tetrahedron of materials science and engineering to sheet steels for automotive chassis. Note that the microstructuresynthesis and processingposition are all interconnected and affect the performancetocost ratio Composition。 semitransparent） 多晶：高孔隙度 （ opaque ） 13 Environmental and Other Effects ? Temperature ? Corrosion ? Fatigue ? Strain Rate High temperature change the structure of ceramics and cause polymers to melt or char Low temperature cause a metal or polymers to fail in a brittle manner, even though the applied loads are low. Figure Increasing temperature normally reduces the strength of a material. Polymers are suitable only at low temperatures. Some posites, special alloys, and ceramics, have excellent properties at high temperatures TEMPERATURE Figure A section through a jet engine. The forward pression section operates at low to medium temperatures, and titanium parts are often used. The rear bustion（尾部燃燒） section operates at high temperatures and nickelbased superalloys are required. The outside shell experiences low temperatures, and aluminum and posites are satisfactory. (Courtesy of GE Aircraft Engines.) Figure A variety of plex ceramic ponents, including impellers（葉輪） and blades, which allow turbine engin
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