Прочитайте текст и выполните следующие за ним задания Metals and Alloys
From the earliest times metals and their alloys were and are referred to as the basic engineering materials. Lately new branches of industry have been developed, for example, electronic, atomic and space industries. The need for new metallic materials has enormously increased. Metals which were practically unheard of before, such as germanium, plutonium and thorium have come to light. Besides, high-temperature alloys for power plants capable of withstanding oxidation and erosion, new ferro-magnetic materials, constructional steels intended for operating under severe stresses and at extremely high or low temperatures have been developed.
Each metal or alloy possesses a certain distinct combination of properties which differs it from other metals and alloys and by which metals and alloys are determined for a given engineering application. This combination of properties may be varied by alloying with other elements.
Before starting to study the properties of metals and alloys we should get an idea of what the terms “pure metal” and “alloys” mean. The term “alloy” is commonly used to describe a metallic solid containing two or more metals and metalloids. The properties of an alloy are influenced by the properties of the elements it consists of. As a rule, alloys are defined by their dominant element which is present in a quantity over 50% (per cent) by weight, the remainder are alloying elements and impurities. There are a lot of alloys, for example, copper-base alloys, aluminium-base alloys and so on.
The term “pure metal” is used for materials from which almost all chemical elements but one are eliminated.
The designation “metal” is sometimes applied in metallurgy to any metallic materials without making any distinction between a pure metal and an alloy. The first definition of the word “metal” was formulated by M. V. Lomonosov in the following way: “A metal is a bright solid that can be forged”. This definition is still true. The metallic luster and the ability for plastic deformation are, in fact, looked upon as the characteristic features of metals. The most important feature of metals, however, is their high electrical conductivity which decreases as the temperature is raised.
In conclusion it’s necessary to mention that metals and alloys are the most important engineering materials due to their excellent properties.
10. Выпишите из текста 10 интернациональных слов и переведите их.
11. Выпишите из текста 5 существительных, 5 прилагательных и 4 наречия образованных с словообразовательных суффиксов.
12. Выпишите из текста 3 словосочетания модальный глагол или его эквивалент + инфинитив.
13. Подчеркните в тексте 5 сказуемых в страдательном залоге.
14. ответьте на следующие вопросы, опираясь на текст.
1. What new metals have recently come to light?
2. What does the term “alloy” mean?
3. What determines the properties of an alloy?
4. What does the term “pure metal” mean?
5. What is the most important feature of metals?
