An alloy is a mixture of one or more metals with other elements. Composites are also a mixture of multiple elements, but do not contain metals. Alloys are either homogenous or heterogenous mixtures whereas composites are always heterogenous.
Ferrous metals contain iron whereas non-ferrous metals do not.
Aluminium is the worlds most abundant non-ferrous metal, however it is difficult to extract, Bauxite being he most common source of it. Pure Aluminium is lightweight, resistant to corrosion, ductile and malleable, but quite soft and has low strength. Aluminium alloys are designed to improve its strength, casting and working properties or to make it heat-treatable. Finally, aluminium can be recycled repeatedly, and over 60% of all the aluminium ever produced is still in use today.
| Advantages | Disadvantages |
|---|---|
| Lightweight compared to steel | Weak compared to steel |
| Can be cast, extruded, rolled, machined etc. | Soft |
| Can be joined through a variety of processes including welding, riveting, adhesives and even soldering. | Difficult to extract |
| Resistant to corrosion due to the oxide layer that forms when it reacts with the atmosphere | |
| Non-toxic, non-magnetics |
Brass is a non-ferrous, yellow decorative metal, that comprises of copper and zinc. Its hardness can be varied with the ratio between the two. It casts and machines well. Its surface tarnishes due to oxidisation and it conducts electricity. Gilding metal comprises mainly of copper, giving the alloy a deeper, more golden colour. Pinchbeck is a brass which looks very similar to Gold and is mixed for its resemblance. Brass is mainly used to make plumbing fittings, ornaments, door furniture, gears, bearings and instruments and electrical switchgear.
Pewter is a white metal (a light coloured alloy), which was used extensively in the Middle Ages to produce tableware, holloware and plateware. it declined with the introduction of mass-produced ceramics and glass which now fall in its place. It is an alloy between tin and copper. It is quite a soft metal that can be shaped easily by hand tools and machine tools. Due to its low melting point, it is suitable for casting. The properties of this material aren’t particularly practically viable so it is mainly used as a decorative metal as a substitute for silver.
Bronze is a copper-based alloy, and has roughly 12% tin. Most commonly used for sculpture, coinage, some musical instruments and ships’ fittings, but is now superseded by Stainless Steel. Phosphor Bronze, has a very small fraction of Phosphorus to increase resistance and stiffness of the alloy. It has a low coefficient of friction, meaning it is ideal for bearings. Gunmetal is another type of bronze used originally to make guns, it casts well and can be used for valves and fittings in steam and hydraulics systems.
CFRP is similar to fibre glass. Carbon fibre is woven into a textile material and resin, such as epoxy resin, is applied and allowed to cure. The resulting material has the best strength to weight ratio of all construction materials, better than steel. It is an improvement on glass fibre reinforced plastic but is much more expensive.
CFRP is often used in the manufacture of expensive sports cars, competition bikes and motorbikes, where strong and light materials are critical for the functionality as weight is kept to a minimum and yet the strength is retained. Fighter aircraft also take advantage of these impressive qualities in the use of Carbon fibre composites.
Fibreglass is a relatively modern composite material (invented it in the late 30s) and industry it is usually referred to as Glass Reinforced Plastic.
GRP is made of strands of glass where each individual glass fibre is very fine with a small diameter and they’re woven to form a flexible fabric. This flexible fabric is usually put in a mould where polymer resin is added, along with a catalyst to hasten the reaction. This process is repeated for many layers of GRP. Once allowed to dry and cure, the resulting material is both strong and light, which can be sanded and painted for a smooth and smart aesthetic.
These are ferrous alloys, where small amounts of Carbon are alloyed with iron and other metals to make Steel. There are 3 main types of steel: Mild Steel, which has a low Carbon content, meaning it can’t be hardened or tempered, but it has sufficient strength, malleability and ductility for common purposes; Tool Steel, has a greater Carbon content, it must be tempered to allow Carbon to diffuse out and controls the balance between Hardness and Toughness to make wood chisels, clock springs etc; and Stainless Steel which, with the addition of Chromium, has many applications where high strength and resistance are required. The steel used in utensils, cutlery and cookware use 403 grade steel which has both Chromium for strength, and Nickel to improve its polish.
| Mild steel | Tough, high tensile strength, can be case hardened but rusts easily as is mainly Iron. |
|---|---|
| Tool steel | Tough, can be hardened and tempered. Used for drills. |
| Stainless steel | Tough, resistant to rust and stains. Cutlery, medical equipment. |