Nonferrous Metals & Alloys

Nonferrous Metals Ferrous Alloys – alloys contain iron Nonferrous Metals – metals do not contain iron such as Copper (Cu), Aluminum (Al) and Titanium (Ti) Ferromagnetic Metals – ferrous or those respond to magnetic field (primarily, Iron (Fe), Nickel (Ni) and Cobalt (Co))

Copper is one of the few metals exists in nature in pure metallic form. It has good corrosion resistance, superior electrical conductivity, excellent heat conductivity and good strength. There is also a variety of alloys (namely brass & bronze) offers a wide range of special properties. Copper & Copper Based Alloys Pure copper and its alloys are commonly used. Its classification is regulated by Copper Development Association (CDA) determined by its chemical compositions.

Pure Copper Pure Copper – A FCC structured metal with excellent electrical & thermal conductivity. Depending on percentage of major impurities Oxygen, industrial copper are three classifications. Electrolytic Tough-Pitch (ETP) Copper – >99.9% copper and ~0.04% oxygen used widely for wiring, plates and strips etc. Oxygen-Free Copper – contains 99.95% copper and it is more expensive Deoxidized Copper – all oxygen in copper is converted to pentoxide (P 2 O 5 ).

Copper Alloys Brass – copper alloys with up to 40% Zinc (Zn) and other materials include Aluminum (Al), Tin (Sn), Nickel (Ni) etc. Strength of Cu-Zn alloy increases as concentration of Zn increase. Adding Manganese, iron and tin could increase its tensile strength and lead can increase machinability

Bronze – primarily a copper-tin alloy. There are also silicon and aluminum bronze with improved tensile strength, hardness and toughness Copper Alloys

Beryllium Copper – high strength copper alloy with addition of small amount of beryllium (Be). It has the highest strength among all copper alloys (stronger than low carbon steel).

Copper Alloys Brass – a alloy of copper with up to 40% Zinc (Zn) with a distinct yellow color. Yellow brass – copper alloyed with 30% Zn and it has the best combination of strength and ductility. It is widely used in application such as heat exchanger Lead brass – 3% lead added to yellow brass to increase machinability (certainly, it lowers the ductility) Red brass – copper alloyed with 15% Zn Other brass alloys – copper alloyed with aluminum (Al), Tin (Sn), and Nickel (Ni) In general, the purpose of additional alloying element is to improve or obtain special properties.

Copper Alloys Bronze – originally Copper alloyed with Tin. Bronze can be obtained by alloying copper with almost all other elements except Zinc. Modern bronze – usually Copper alloyed with Tin plus 0.3% Phosphorus (P) Silicon bronze – contains 1% to 3% Silicon in place of Tin. It has typical application of seawater environment Aluminum bronze – contains up to 10% Aluminum in place of Tin. It is quite hard and tough. It resist wear and fatigue. It can also be used in corrosive condition

Copper Alloys Beryllium Copper – addition of 0.6% to 2% of Beryllium (Be) to copper creates a series of alloy with highest strength among all copper alloy. Commercial Beryllium Copper also contain 0.2% to 2.5% Cobalt (Co). It is widely used in electrical contact springs, springs, gears and valves etc. The major disadvantage are cost of Beryllium and health hazard.

Aluminum and Aluminum Alloys Aluminum is third most commonly used metal standing behind Iron and Steel. Classification – four digits number with the first indicating alloying elements. Sometime, a letter code also used to identify heat treatment method. All aluminum alloys have a relative low stiffness. Its elastic deformation is three times of that of steel. The low modulus is also not sensitive to alloying element. Pitting is a localized corrosion. Anodizing is a widely used method for surface treatment and coloring.

Heat Treatment of Aluminum Alloys Non-heat-treatable and heat-treatable are two types of aluminum alloys. In the former case, the alloys can not be hardened using heat treatment. Solution Treatment – alloyed aluminum is heated to dissolve the alloying elements into the aluminum and then quenched Age hardening – holding aluminum alloy at low temperature so that copper precipitates from the solid solution to form hard inter-metallic compound CuAl 2 Annealing – a heating and then slow cooling process to reduce any possible strain hardening

Zinc and Magnesium Alloys Both Zinc and Magnesium (Mg) have very low melting temperature which made them ideal casting materials. Zinc – has a hexagonal close-packed (HCP) crystal structure. Its high corrosion resistance and adheres to substrate very well made it good coating material for steels. As shown earlier, it can also be used to alloy with aluminum. Magnesium – lightest of all commonly used metal. It used primarily in alloy form with aluminum, zinc etc.

Precious Metals High cost is where the name of these materials come from. Although the quantity they are used is small, they are extremely important to modern society. Platinum (Pt) – one of the most inactive metals, which makes it a good corrosion resistant material. It has superior resistance to high temperature oxidization, nitric acid (but not chlorine at elevated temperature) Silver (Ag) – widely used in electronics and photographic emulsions. Gold (Au) – extensively used in electrical contacts due to its superior electrical conductivity and resistance to oxidization.

Summary Although Iron and Steel are the two most commonly used materials. Non-ferrous materials are playing an important and un-replaceable role in modern society.