Metal Properties: Aluminum, Silver, Gold, Steels & Alloys

Metal Properties: Aluminum, Silver, Gold, Steels

Aluminum: Properties and Uses

Aluminum: Very abundant but can be difficult to extract in pure form. Common processes and uses include welding, casting, forging and structural support. Key characteristics:

• Very light — low density.
• Malleable and ductile.
• Good conductor of heat and electricity.
• Relatively soft compared with many metals.
• When exposed to oxygen, it forms a thin, very stable oxide layer that covers and protects the underlying metal.

Silver: Properties and Uses

Silver: Relatively scarce and of high economic value (widely used in jewelry). Key characteristics:

• Very flexible and highly malleable.
• The best conductor of electricity and heat among common metals, which makes it valuable in electronics.
• Noted for its very high reflectivity, which explains its use in mirrors.

Gold: Properties and Uses

Gold: Relatively scarce and of high economic value (widely used in jewelry). Key characteristics:

• Exceptionally flexible and the most malleable common metal.
• Very high corrosion resistance and resistance to attack by the majority of chemical agents.
• Often used in the form of very thin plates to cover and protect valuable objects, including components for space probes and satellites.
• Good conductor of both electricity and heat.

Alloys: Types and Characteristics

Alloys: An alloy is a combination of various metals, often containing small amounts of some non-metals. Alloys are developed to improve the properties of the original components. They are usually classified according to the metal present in the highest proportion.

Ferrous Alloys and Steel

Ferrous alloys are those whose primary component is iron. The principal ferrous alloy is steel, which is formed by the mixture of iron with a percentage of carbon always less than 2%.

There are two main types of ferrous alloys (steel):

Carbon Steel

Carbon steel is steel with carbon as its principal alloying element. Carbon steels constitute almost 90% of the steel used in industry. Its main feature is mechanical strength, which depends on the carbon content: more carbon generally increases hardness and strength.

Alloy Steel

Alloy steel is formed by adding elements other than carbon to steel (such as chromium, nickel, molybdenum, etc.) to obtain desired properties. These steels are characterized by properties modified beyond what carbon alone provides, such as improved strength, toughness or corrosion resistance.

Non-Ferrous Alloys

Non-ferrous alloys are based on metals other than iron. Major non-ferrous alloys include bronze, brass, and duralumin.

Bronze

Bronze is an alloy of copper and tin. It is stronger than pure copper and resists corrosion. Its mechanical properties can be similar to those of steel in some applications. Today bronze is used for decorative items, sculptures and for the manufacture of metal elements exposed to marine environments.

Brass

Brass is a copper–zinc alloy. It provides greater hardness and ductility than pure copper. A notable property of brass is that it is non-sparking on impact, unlike many other metals and alloys, which makes it suitable for items used in the presence of flammable substances. Other characteristics include good cold formability, wear resistance and corrosion resistance. Brass is commonly used in hardware and the manufacture of valves, bolts and nuts.

Duralumin

Duralumin is an aluminum alloy combined with other metals. The most common alloying elements are copper, magnesium, manganese and zinc. This alloy addresses the relative lack of hardness and strength of pure aluminum, providing improved strength while remaining lightweight.