机械设计制造及其自动化专业英语翻译

机械设计制造及其自动化专业英语翻译Unit 1 Metals金属 The use of metals has always been a key factor in the development

机械设计制造及其自动化专业英语翻译 Unit 1Metals 金属 The use of metals has always been a 在人类社会的发展中，金属的应用 key factor in the development of the social 。100 起着关键性的作用构成物质的大约种 systems of man. Of the roughly 100 basic 。 基本元素中，大约有一半为金属金属和非 elements of which all matter is composed, 。 金属之间的区别不是特别明显最基本的定 about half are classified as metals. The 义集中在元素原子间存在的连接形式和与这 distinction between ametal and anonmetal 。 些原子相关联的电子的某些特性然而，在 clear-cut is not always .The most basic 实际应用中，可以将具有某些特性集合金属 centers around definition the type of 。 定义为某种元素 bonding existing between the atoms of the characteristics element, and around the of certain of the electrons associated with these atoms. In amore practical way, however, ametal can be defined as an element which has aparticular package of 除了少数例外金属在常温下是固态 properties. 。。 的它们是热和电的良导体，不透光它们 crystalline Metals are when in the 。 往往具有较高的密度许多金属具有延展性， solid state and, with few exceptions (e.g. 也就是说，在不被破坏的情况下它们的形状 ambient mercury), are solid at temperatures. 。 在外力的作用下可以发生变化引起永久变 They are good conductors of heat and 形所需的力和最终使金属断裂所需的力相当 opaque electricity and are to light. They 大，尽管发生断裂所需的力远没有像所预期 usually have acomparatively high density. 。 的撕开金属原子所需的力那么大 ductile Many metals are -that is, their shape can be changed permanently by the application of aforce without breaking. The forces required to cause this deformation and those required to break or fracture a metal are comparatively high, although, the fracture forces is not nearly as high as would be expected from simple 从我们的观点来看，在所有的特性中结 consideration of the forces required to tear 。 晶性是最重要的结晶体是这样一种结构， apart the atoms of the metal. 组成它的原子定位在规则的三维排列中，仿 One of the more significant of these 。 佛位于三维棋盘的方格的角上原子间距随 characteristics from our point of view is 着原子大小呈规律性变化，原子间距是金属 that of crystallinity. Acrystalline solid is 。 的一种特性三维排列的轴线决定了晶体在 one in which the constituent atoms are 。 空间中的方向在工程实践中应用的金属由 located in aregular three-dimensional array 。 大量的晶体组成，这些晶体称之为晶粒在 as if they were located at the corners of 。 大多数情况下，晶粒在空间中是自由排列的 the squares of athree-dimensional 。 在原子范围内，晶粒之间相互接触紧密结合