6. Alloy properties

An alloy is a metal that is composed of two or more different elements. For example, brass is copper that has been alloyed with zinc (meaning it has some zinc added to it). Stainless steel is iron that has been alloyed with chromium, and often nickel.

Alloys all have different properties depending on the different elements they are composed of, and how much of each element is present. An alloy like stainless steel is designed for corrosion resistance, whereas an alloy like inconel (made from nickel, chromium, and small amounts of several other elements) is designed to be able to operate at high temperatures.

One property that almost all alloys have is that their melting point is lower than the pure form of their base metal. For example, stainless steel has a melting point that is lower than pure iron, and brass has a melting point lower than pure copper.

Smart alloys have unusual properties. Nitinol is an alloy of nickel and titanium, and is known as a shape memory alloy. If nitinol is bent out of shape, it returns to its original shape when it is either heated or an electric current is passed through it. This property makes it useful for making spectacle frames - they return to their original shape if they are put in hot water after bending them.

Task 1. Say whether these sentences are true or false

1. Stainless steel is iron that has not been alloyed with chromium, and often nickel.

2. Alloys have different properties depending on the different elements they are composed of.

3. Stainless steel has a melting point that is higher than pure iron.

4. Brass has a melting point higher than pure copper.

5. Smart alloys have usual properties.

Task 2. Make the sentences complete:

Brass is	a) is designed for corrosion resistance
Alloys all have different properties	b) is an alloy of nickel and titanium, and is known as a shape memory alloy
Stainless steel	c) a melting point that is lower than pure iron
Stainless steel has	d) depending on the different elements they are composed of
Nitinol	e) copper that has been alloyed with zinc

Task 3. Mach the term with its definition

Brass	a)something serving as a model or basis for imitations or copies
2. Property	b) a yellow alloy of copper and zinc
3. Resistance	c)the ability not to be affected by something, esp. adversely
4. Melting point	d) an attribute, quality, or characteristic of something
5. Original	e)the temperature at which a given solid will melt

Task 4. Fill in the gaps:

Smart alloys have __1____ properties. Nitinol is an alloy of nickel and, and ___2___ is known as a shape memory alloy. If nitinol is bent out of ____3__, it returns to its original shape when it is either __4___ or an electric current is passed through it. This property makes it useful for making spectacle frames - they return to their __5___ shape if they are put in hot water after bending them.

1. titanium; B original; C heated; D shape; E unusual.