专业材成英语 6.doc

专业材成英语 6.doc2. 2. 4 Iron—Carbon Equilibrium Diagram
铁碳合金平衡相图
The struetural form of pure iron at room temperature is called fe rrite a - 。Ferrite is sof t and Since ferrite has a body-centred cubic s trueture, the inter~atomic spaces are small and pronouncedly oblate, and cannot readily accommodate even a small carbon
，原子间距很小而无法容纳很小的碳原 子 Therefore, solub订ity of carbon in
ferrite is very low, of the order of 0. 006% at room temperature. The maximum carbon content in ferrite is 0. 05%
at 723°C addition to carbon,所以室温下碳在铁中的溶解度很低，最高 % 723°C时 a certain amount of silicon, manganese and phosp horous may be found in . 05%,除了碳外， 铁素体也含有…定量的硅、猛和磷
The face~centred modification of iron is called austenite or y-i 。It is the stable form of pure 让on at temperatures between 910°C and 1400°C・这些是纯铁在910°C至 140 0°C温度间的稳定形式
At its stable temperature austenite is soft and duetile and conse quently, is well suited for manufacturing processes・
在稳定温度下奥氏体柔软，可塑，因此很适用于制造过程
The face~centred cubic strueture of iron has larger inter~atomic spacing than in ferrite・铁的面心立方结构比铁素体具有更大的中心原子间 距 Even so, in FCC strueture the interstices are barely large enough to accommodate carbon atoms, and lattice strains are produced・尽管女口 此，面心立方结构的间隙也难以大到足够容纳碳原子As a
resuIt, not all the interstitial sites can be filled at any on