What is the composition of heating wire ?Why is nichrome wire used as heating element?

The nichrome wire is an alloy of nickel (60%) and chromium 40% metals. Nichrome wire is used as heating element because of the following reasons: 

1. It has high resistance, high melting point and radiates heat easily.
2. It does not react with oxygen even at high temperature.
3. It lasts for longer time. 

Nichrome is a non-magnetic alloy of nickel and chromium. Nichrome is widely used in heating elements. It is wound in wire coils to a certain electrical resistance, and current passed through to produce heat.Nichrome is good, steel or stainless steel should also work ok and may be preferred if you need less heat and more strength.Both varieties of nichrome wire  have maximum operating temperatures of about 1100°C – 1200°C (¹) and melting temperatures above 1400°C (¹). The chromium will form an oxide layer on the wire's surface which protects the wire from corrosion.

Nichrome is used for making heating element of electrical appliances. Because nichrome does not oxidize and burn easily at high temperature i.e.it has higher melting and boiling point than metals. Thus it does not melt even when a large amount of heat is produced due to passage of current.Nichrome wire, an alloy of nickel and chromium, and often iron (or other elements) is good for making heaters but not lamps. At rated voltages, nichrome will glow orange-red, not the bright white that is needed for illumination. If you increase the voltage to get a brighter color, the nichrome will burn open (melt.)