材料科学与工程导论双语课件教学课件 ppt 作者 陈克正 王玮 刘春延 等编Chapter 1.ppt

Steels, as you may know, have been used in manufacturing for more than a hundred years, but they probably existed in a crude form during the Iron Age, thousand of years ago. In the manufacture of automobile chassis, a material is needed that possessed extremely high strength but is easily formed into aerodynamic contours. Another consideration is fuel-efficiency, so the sheet steel must also be thin and lightweight. The sheet steels should also be able to absorb significant amounts of energy in the event of a crash, thereby increasing vehicle safety. These are somewhat contradictory requirements. The Materials Selection Process Thus, in this case, materials scientists are concerned with the sheet steel’s (1) composition; (2) strength; (3) weight; (4) energy absorption properties; (5) malleability (formability). The Materials Selection Process Synthesis /processing Properties Structure/composition Performance The Materials Selection Process Materials scientists would examine steel at a microscopic level to determine if its properties can be altered to meet all of these requirements. They also would have to consider the cost of processing this steel along with other considerations. How can we shape such steel into a car chassis in a cost-effective way? The Materials Selection Process Will the shaping process itself affect the mechanical properties of the steel? What kind of coatings can be developed to make the steel corrosion resistant? In some applications, we need to know if these steels could be welded easily. From this discussion, you can see that many issues need to be considered during the design and materials selection for any product. The Materials Selection Process Future of Materials Science Design of materials having specific desired characteristics directly from our knowledge of atomic structure. Miniaturization: “nanostructured” materials, with microstructure that has length scales between 1 and 100 nm with unusual properties. Elect