What do you mean by thermite process?

                        A thermite mixture using iron (3) oxide

Thermite is a pyrotechnic composition of metal powder fuel and metal oxide. When ignited by heat, thermite undergoes an exothermic oxidation-reduction reaction. Most varieties are not explosive but can create brief bursts of high temperature in a small area. Its form of action is similar to that of other fuel-oxidizer mixtures, such as black powder.
Thermites have diverse compositions. Fuels include aluminium, magnesium, titanium, zinc, silicon, and boron. Aluminium is common because of its high boiling point. Oxidizers include boron(III) oxide, silicon(IV) oxide, chromium(III) oxide, manganese(IV) oxide, iron(III) oxide, iron(II,III) oxide, copper(II) oxide, and lead(II,IV) oxide. 
 

Chemical reactions

thermite reaction using iron(3) oxide.

A thermite reaction using iron(III) oxide. The sparks flying outwards are globules of molten iron trailing smoke in their wake.

The aluminium reduces the oxide of another metal, most commonly iron oxide, because aluminium forms stronger bonds with oxygen than iron:

Fe₂O₃ + 2 Al → 2 Fe + Al₂O₃

The products are aluminium oxide, free elemental iron, and a large amount of heat. The reactants are commonly powdered and mixed with a binder to keep the material solid and prevent separation.
The reaction is used for thermite welding, often used to join rail tracks. Other metal oxides can be used, such as chromium oxide, to generate the given metal in its elemental form. Copper thermite, using copper oxide, is used for creating electric joints in a process called cadwelding:

3 CuO + 2 Al → 3 Cu + Al₂O₃

Some thermite-like mixtures are used as pyrotechnic initiators such as fireworks.
Thermites with nanosized particles are described through a variety of terms, such as metastable intermolecular composites, super-thermite, nano-thermite, and nanocomposite energetic materials.

Iron thermite

The most common composition is the iron thermite. The oxidizer used is usually either iron(III) oxide or iron(II,III) oxide. The former produces more heat. The latter is easier to ignite, likely due to the crystal structure of the oxide. Addition of copper or manganese oxides can significantly improve the ease of ignition.
The original mixture, as invented, used iron oxide in the form of mill scale. The composition was very difficult to ignite.

Copper thermite

Copper thermite can be prepared using either copper(I) oxide (Cu₂O, red) or copper(II) oxide (CuO, black). The burn rate tends to be very fast and the melting point of copper is relatively low so the reaction produces a significant amount of molten copper in a very short time. Copper(II) thermite reactions can be so fast that copper thermite can be considered a type of flash powder. An explosion can occur and send a spray of copper drops to considerable distance.
Copper(I) thermite has industrial uses in e.g. welding of thick copper conductors ("cadwelding"). This kind of welding is being evaluated also for cable splicing on the US Navy fleet, for use in high-current systems, e.g. electric propulsion.

Source:   http://en.wikipedia.org/wiki/Thermite