I. Copy the underlined words and word-combinations, translate them into Ukrainian and learn them.

III. Fill in the following table, using the text.

Non-ferrous metals

Although ferrous alloys are specified for more engineering applications than all non-ferrous metals combined, the large family of non-ferrous metals offers a wider variety of characteristics and mechanical properties. For example, the lightest metal is lithium, 0.53 g/cm³, the heaviest, osmium, weighs 22.5 g/cm³ – nearly twice the weight of lead. Mercury melts at around - 38°F, and tungsten, the metal with the highest melting point, liquefies at 6, 170°F.

Availability, abundance, and the cost of converting the metal into useful forms – all play important parts in selecting a non-ferrous metal. One ton of earth contains about 81, 000 g of the most abundant metal of land, aluminium. One ton of sea water, on the other hand, contains more magnesium than any other metal (about 1, 272 g). All sources combined, magnesium is the most abundant metal on earth. But because magnesium is difficult to convert to a useful metal, it may cost several times that of the least expensive and most easily produced metal, iron billet.

Although nearly 80% of all elements are called “metals”, only about two dozen of these are used as structural engineering materials. Of the, balance, however, many are used as coatings, in electronic devices, as nuclear materials, and as minor constituents in other systems.

Aluminium

Aluminium is lightweight, strong, and readily formable. Aluminium and its alloys, numbering in the hundreds, are available in all common commercial forms. Because of their high thermal conductivity, many aluminium alloys are used as electrical conductors.

Commercially pure aluminium has a tensile strength of about 13, 000 psi. Cold-working the metal approximately doubles its strength. For greater strength aluminium is alloyed with other elements such as manganese, silicon, copper, magnesium or zinc. Some alloys are further strengthened and hardened by heat treatment. Most aluminium alloys lose strength at elevated temperatures, although some retainsignificant strength to 500^o F.

I. Copy the underlined words and word-combinations, translate them into Ukrainian and learn them.