There was a time when aluminium was an item for royal families and noblemen to show off and a representation of national industrial strength due to its rarity and the difficulty in metallurgy.  At the 1855 Paris Expo, a small sample of aluminium was exhibited beside the priceless French crown jewels, marking the debut of this new metal introduced as an invaluable piece of artwork to the public. In 1888, a 9-inch aluminium pyramid made of 100-ounces of solid aluminum capped the top of the Washington Monument. Aluminium was the metal of choice by the architects for its rust and corrosion resistance. The pyramid, being the largest piece of aluminum blocks in those days, was displayed at Tiffany"s jewelry store in New York before it was placed at the top of the Washington Monument.  Despite its high value, few people worked in the aluminium metallurgy industry as the process was highly complicated and caused explosion easily. The low-yield volume made aluminium a treasure amongst all metals.

 

Aluminium is one of the 92 metallic elements discovered on earth so far. The content of aluminium on earth crust is approximately 8%, ranking it the third most abundant element after oxygen (47%) and silicon (27%). Despite the fact that aluminium has a far richer deposit than iron, aluminium metallurgy has a history of less than 200 years, because it is a chemically reactive material which has made it difficult to extract from ores. It was not until the late 18th century when the electrolytic process was invented for its mass production. Nowadays, aluminium is known as the Second Metal for its production and consumption is only slightly behind steel. Aluminium has a unique and unbeatable combination of properties, making it a popular metal for industrial development. It is light with density of 2.7g/cm3, which is about one third of that of steel and copper. Other chemical properties include good ductility, thermal and electrical conductivities, thermal stability, and radiation shield. 

 

Pure aluminium is soft and low strength, but its properties can be highly improved when alloying with other metals. Aluminium-copper alloy, for instance, is stiff and corrosion resistant and has similar strength as steel and maintains a shiny appearance for long. It is commonly used in making jewelries and in the construction industry. Aluminium-magnesium alloy, another widely used alloy type, greatly improves the stiffness while maintaining the beauty of being lightweight.  It is commonly used in the manufacture of fuselages and vessels. 

 

With its good ductility, aluminium can be shaped into filaments or aluminium foils and is extensively used in manufacturing wires and cables in the telecommunication and packaging industries. Aluminium’s electricity conductivity generally is about two third of copper’s, but its density is only one third of copper’s. Compared with copper wire of the same weight and length, aluminium wire’s electricity conductivity is twice that of copper’s. High-voltage cables are therefore mostly made of aluminium. In addition, the light weight property of aluminium also helps reduce the cost of building large number of supporting structures. 

 

Aluminium’s heat conductivity is three times higher than iron, and is commonly used in making heat-exchangers and radiators. Most cookware is also made of aluminium, a preferred choice over iron due to its rust resistance and longer lifespan.

 

Another valuable characteristic of aluminium is that it is recyclable. The recycling of secondary aluminium requires only 5% of energy used in producing primary aluminium. The recycled aluminium retains the original metal properties but produced at a much lower cost. Aluminium is therefore an ideal solution to environmental protection and energy saving.