Question

Define an alloy. How are alloys prepared? How do the properties of iron change when:
(i) a small quantity of carbon
(ii) nickel and chromium are mixed with it.

Answer 1

Hint: A combination of metal or metals when combined with one or more other elements or metals is known as an alloy. An alloy is typically an impure metal, where impurities denote undesirable elements.

Complete step by step answer:
-A combination of a metal with at least one other metal or non-metal is known as an alloy.
-The combination of metal-metal or metal-non metal must be a part of a solid solution, a compound, or a mixture with one another to be considered as an alloy.
-Most of the alloys are formed by mixing metals in their molten state, then the mixture is poured into metal or sand molds and then is allowed to solidify. Generally, the major ingredient of alloy to be prepared is melted first and then the other metal(s) or nonmetal(s) are added making sure it is completely dissolved with the major ingredient.
-Examples of some alloys are, combining the metallic elements of gold and copper gives red gold, gold, and silver in combination becomes white gold, silver, and copper in combination produces sterling silver.

-The properties of alloys are well controlled by the impurities present in the alloy. The properties of alloy can change when-
(i) we add a small amount of carbon in an alloy. The alloy has high strength and can be altered by heat treatment which on solidifying becomes strong and hard. The formed alloy is known as steel.
(ii) we add nickel and chromium in steel, the high resistance is enhanced with which heat resistance and tensile strength also increase. Alloy thus now formed becomes stainless steel which is strong and corrosion-resistant.

Note: There are certain terms associated with an alloy which we must know. The metal in which another metal is added forms the base hence is known as the base metal. The base metal is also known as primary metal, or the matrix or the solvent. The other metal which is mixed with base metal is known as a secondary constituent of the solutes. If an alloy involves the combination of only two types of atoms, or three types of atoms, or four types of atoms, or five types of atoms then the formed alloy is known as binary alloy, ternary alloy, quaternary alloy, quinary alloy respectively.