Nickel

Nickel is a naturally occurring, lustrous, silvery-white metallic element. It is the fifth most common element on earth and occurs extensively in the earth's crust. However, most of the nickel is inaccessible in the core of the earth.

 Nickel metal’s key characteristics are:

• High melting point, 1453 ºC
• Resists corrosion and oxidation
• Very ductile
• Alloys readily
• Magnetic at room temperature
• Can be deposited by electroplating
• Has catalytic properties

Reflecting these characteristics, nickel is widely used in over 300,000 products for consumer, industrial, military, transport, aerospace, marine and architectural applications. The biggest use is in alloying - particularly with chromium and other metals to produce stainless and heat-resisting steels. These are used for pots and pans, kitchen sinks etc, as well in buildings, food processing equipment, medical equipment and chemical plants.
About 65% of the nickel which is produced is used to manufacture stainless steels. Another 20% is used in other steel and non-ferrous alloys - often for highly specialized industrial, aerospace and military applications. About 9% is used in plating and 6% in other uses, including coins, electronics, and in batteries for portable equipment and hybrid cars. In many of these applications there is no substitute for nickel without reducing performance or increasing cost.
Nickel is essential for healthy plant life. As a result, it is found naturally in most vegetables, fruits and nuts, and in the food products derived from them, for example – chocolate and wine.

From  http://www.nickelinstitute.org/NickelUseInSociety/AboutNickel/NickelMetaltheFacts.aspx

Bronze

Bronze is an alloy made of copper and another metal, usually tin. Compositions vary, but most modern bronze is 88% copper and 12% tin.

Although at one time bronze was any alloy consisting of copper with tin and brass was an alloy of copper with zinc, modern usage has blurred the lines between brass and bronze. Now, copper alloys generally are called brass, with bronze sometimes considered a type of brass.

Bronze usually is a golden hard, brittle metal. The properties depend on the specific composition of the alloy as well as how it has been processed.

From  http://chemistry.about.com/od/alloys/f/What-Is-Bronze.htm

Brasses

Brass is the generic term for a range of copper-zinc alloys with differing combinations of properties, including strength, machinability, ductility, wear-resistance, hardness, colour, antimicrobial, electrical and thermal conductivity, and corrosion resistance.

Brasses set the standard by which the machinability of other materials is judged and are also available in a very wide variety of product forms and sizes to allow minimum machining to finished dimensions.  Brass does not become brittle at low temperatures like mild steel.

Brass also has excellent thermal conductivity, making it a first choice for heat exchangers (radiators). Its electrical conductivity ranges from 23 to 44% that of pure copper.

Nickel Silvers

These silver coloured copper-nickel-zinc alloys containing 10-20% nickel can be regarded as special brasses.  In most respects they show similar corrosion characteristics to the brasses, but the higher nickel versions have superior tarnish resistance and resistance to stress corrosion cracking.  They are available in all forms and are used for tableware (silver-plated to give EPNS), telecommunication components, food manufacturing equipment, jewellery, model making, tool brush anchor wire and pins, musical instruments, e.g. ‘silver bands’, flutes, test probes and contact springs.

Colours of Brass

Brasses have a range of attractive colours,red, yellow, gold, brown, bronze, silver. Brass with 1% manganese will weather to a chocolate brown colour.  Nickel silvers will polish to a brilliant silver colour. Brasses are easy to shape and, with all these colours available, it is not surprising that architects and designers have used brasses to enhance the appearance of new and refurbished buildings, both inside and out.

Brass and Hygiene

Copper and brass are playing a leading role in the fight against hospital-acquired infections such as MRSA and Clostridium difficile. It has been shown that these pathogens, which can be spread by touch, will die in a few hours on copper/brass surfaces. This does not happen on stainless steel or plastic.

Recycling Brass

The brass industry throughout the world is well organised and equipped to recycle products at the end of their long lives and process scrap (swarf and offcuts). Making brass from new (virgin) copper and zinc would be uneconomical and wasteful of raw materials so new brass products are made from recycled scrap, illustrating the sustainable nature of this material.  In the UK brass manufacturers use almost 100% brass scrap.

From http://www.copperalliance.org.uk/copper-and-its-alloys/alloys/brasses

Copper wiki definition

Copper is a chemical element with symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; a freshly exposed surface has a reddish-orange color. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.
The metal and its alloys have been used for thousands of years. In the Roman era, copper was principally mined on Cyprus, hence the origin of the name of the metal as сyprium (metal of Cyprus), later shortened to сuprum. Its compounds are commonly encountered as copper(II) salts, which often impart blue or green colors to minerals such as azurite and turquoise and have been widely used historically as pigments. Architectural structures built with copper corrode to give green verdigris (or patina). Decorative art prominently features copper, both by itself and as part of pigments.
Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase. In molluscs and crustacea copper is a constituent of the blood pigment hemocyanin, which is replaced by the iron-complexed hemoglobin in fish and other vertebrates. The main areas where copper is found in humans are liver, muscle and bone.^[3] Copper compounds are used as bacteriostatic substances, fungicides, and wood preservatives.

From  http://en.wikipedia.org/wiki/Copper

Stainless Steel wiki definition

In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is a steel alloy with a minimum of 10.5%^[1] chromium content by mass.
Stainless steel does not readily corrode, rust or stain with water as ordinary steel does. However, it is not fully stain-proof in low-oxygen, high-salinity, or poor air-circulation environments.^[2] There are different grades and surface finishes of stainless steel to suit the environment the alloy must endure. Stainless steel is used where both the properties of steel and corrosion resistance are required.
Stainless steel differs from carbon steel by the amount of chromium present. Unprotected carbon steel rusts readily when exposed to air and moisture. This iron oxide film (the rust) is active and accelerates corrosion by forming more iron oxide; and, because of the greater volume of the iron oxide, this tends to flake and fall away. Stainless steels contain sufficient chromium to form a passive film of chromium oxide, which prevents further surface corrosion by blocking oxygen diffusion to the steel surface and blocks corrosion from spreading into the metal's internal structure, and, due to the similar size of the steel and oxide ions, they bond very strongly and remain attached to the surface.^[3]
Passivation occurs only if the proportion of chromium is high enough and oxygen is present.

From http://en.wikipedia.org/wiki/Stainless_steel