第一單元
• Types of Materials
材料的類型
Materials may be grouped in several ways. Scientists often classify materials by their state: solid, liquid, or gas. They also separate them into organic (once living) and inorganic (never living) materials.
材料可以按多種方法分類。科學(xué)家常根據(jù)狀態(tài)將材料分為：固體、液體或氣體。他們也把材料分為有機(jī)材料(曾經(jīng)有生命的)和無(wú)機(jī)材料(從未有生命的)。
For industrial purposes, materials are divided into engineering materials or nonengineering materials. Engineering materials are those used in manufacture and become parts of products.
就工業(yè)效用而言，材料被分為工程材料和非工程材料。那些用于加工制造并成為產(chǎn)品組成部分的就是工程材料。
Nonengineering materials are the chemicals, fuels, lubricants, and other materials used in the manufacturing process, which do not become part of the product.
非工程材料則是化學(xué)品、燃料、潤(rùn)滑劑以及其它用于加工制造過(guò)程但不成為產(chǎn)品組成部分的材料。
Engineering materials may be further subdivided into: ①M(fèi)etal ②Ceramics ③Composite ④Polymers, etc.
工程材料還能進(jìn)一步細(xì)分為：①金屬材料②陶瓷材料③復(fù)合材料 ④聚合材料，等等。
• Metals and Metal Alloys
金屬和金屬合金
Metals are elements that generally have good electrical and thermal conductivity. Many metals have high strength, high stiffness, and have good ductility.
金屬就是通常具有良好導(dǎo)電性和導(dǎo)熱性的元素。許多金屬具有高強(qiáng)度、高硬度以及良好的延展性。
Some metals, such as iron, cobalt and nickel, are magnetic. At low temperatures, some metals and intermetallic compounds become superconductors.
某些金屬能被磁化，例如鐵、鈷和鎳。在極低的溫度下，某些金屬和金屬化合物能轉(zhuǎn)變成超導(dǎo)體。
What is the difference between an alloy and a pure metal? Pure metals are elements which come from a particular area of the periodic table. Examples of pure metals include copper in electrical wires and aluminum in cooking foil and beverage cans.
合金與純金屬的區(qū)別是什么？純金屬是在元素周期表中占據(jù)特定位置的元素。例如電線中的銅和制造烹飪箔及飲料罐的鋁。
Alloys contain more than one metallic element. Their properties can be changed by changing the elements present in the alloy. Examples of metal alloys include stainless steel which is an alloy of iron, nickel, and chromium; and gold jewelry which usually contains an alloy of gold and nickel.
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