材料成型及控制工程专业英语- 1.MATERIALS AND THEIR PROPERTIES.ppt

Magnesium alloys have even lower density than aluminum and，as a result，appear in numerous structural applications such as aerospace designs．Aluminum is a fcc material and therefore has numerous (12) slip systems, leading to good ductility．By contrast．magnesium is hcp with only three slip systems and characteristic brittleness． - * - 镁合金的密度比铝合金的还低，因此，设计航空飞行器时大量的结构件用镁合金。铝合金是面心立方结构金属，因此，有12个滑移系，使其延展性好。相反，镁合金是密排六方结构，仅有3个滑移系，易脆断（具有脆性）。 Titanium alloys have become widely used since World WarⅡ．Before that time，a practical method of separating titanium metal from reactive oxides and nitrites was not available. Once formed, titanium’s reactivity works to its advantage．A thin tenacious oxide coating forms on its surface, giving excellent resistance to corrosion. This “passivation” will be discussed in detail later. Titanium alloys，like Al and Mg，are of lower density than ion. - * - 二战以后钛合金被广泛应用，在此之前，还没有通过活性氧和硝酸盐分离钛金属的工艺。一旦形成钛合金，钛的活性显现出其优点。其表面形成致密的氧化膜，使其就有优良的抗腐蚀性。“钝化性”将在后面详细讨论。与Al、Mg一样，钛合金密度比铁低。 titanium－钛nitrite－亚硝酸盐tenacious－顽强的passivation－钝化aerospace－航空宇宙vanadium－钒 reactive oxide－活性氧 Although more dense than Al or Mg，titanium alloys have a distinct advantage of retaining strength at moderate service temperatures, leading to numerous aerospace design applications. Titanium shares the hcp structure with magnesium leading to characteristically low ductility. However，a high temperature bcc structure can be stabilized at room temperature by certain alloy additions such as vanadium. - * - 尽管密度要比Al、Mg高，钛合金的显著特点之一是在中等服役温度下能保持其强度，因此航天中应用多。与镁合金一样，钛合金也是Hcp晶格结构，延展性低。然而，通过添加钒等合金，其高温下bcc晶格结构可以在室温下保存。 titanium－钛nitrite－亚硝酸盐tenacious－顽强的passivation－钝化aerospace－航空宇宙vanadium－钒 reactive oxide－活性氧 Copper alloys possess a number of superior properties. Their excellent electrical conductivity makes copper alloys the leading material for electrical wiring. Their excellent thermal conductivity leads to applications for radiators and heat exchangers. Superior corrosion resistance is exhibited in