Exotic Alloys 301

brittle

A material's unwillingness to be drawn, stretched, or formed. Brittle materials tend to fracture when subjected to these forces.

capacitance-to-volume ratio

The relationship between a material's ability to store an electrical charge and its volume. Tantalum is often used in stereo parts due to its high capacitance-to-volume ratio.

carbides

A compound developed by the combination of carbon with usually chromium, tungsten, or titanium. Carbide is often used to make metal cutting tools due to its hardness and wear resistance.

carburizing

A surface hardening method that heats metal within a carbon-rich environment to increase carbon levels on the metal surface for added hardness. Iron-based superalloys are often used to construct carburizing furnaces.

cast

A manufacturing process that pours a liquid material into a hollow mold until the material cools into a solidified shape. Most cobalt-based superalloys must be cast due to the metal's properties.

clad

Having an outer covering of thin metal, which is often added to insulate or protect the underlying metals. Titanium is sometimes clad to steel when making airplane bodies.

cobalt

A shiny, grayish metal that is brittle and hard with magnetic properties similar to iron. Cobalt is a base element or alloying element in many superalloys.

cobalt-based superalloys

A superalloy with cobalt as the base metal. Cobalt-based superalloys have superior thermal fatigue resistance and corrosion resistance but are very difficult to machine.

coefficient of thermal expansion

The change in density that occurs as a material changes in temperature. A metal typically increases in volume and decreases in density as it is heated.

corrosion resistance

The ability of a material to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Cobalt and titanium have high corrosion resistance.

creep resistance

The tendency of a material to withstand a constant force over an extended period of time. Creep resistance is also known as creep strength.

ductile

A material's ability to be drawn, stretched, or formed without fracturing. Ductile is the opposite of brittle.

electrical discharge machining

EDM. Electrical discharge machining uses a rapid series of electrical sparks to vaporize and remove metal. EDM can be used to machine certain superalloys.

exotic metal

Any metal that does not fit within the major metals categories commonly used in manufacturing. Exotic metals are typically nonferrous, and many exhibit properties that make them favorable for specific advanced applications.

exotic metals

Any metal that does not fit within the major metals categories commonly used in manufacturing. Exotic metals are typically nonferrous and many exhibit properties that make them favorable for specific advanced applications.

gas tungsten arc welding

A very precise arc welding process that uses a nonconsumable tungsten electrode. The American Welding Society abbreviation for gas tungsten arc welding is GTAW.

hardness

The measure of a material's ability to resist scratching and penetration. Most superalloys are hard metals.

high performance alloy

A metal alloy consisting of numerous alloying elements that is very expensive and designed to perform under intense conditions such as elevated temperatures. High performance alloys are also known as superalloys.

hot corrosion resistance

The ability of certain materials to resist the natural tendency to experience accelerated corrosion at high temperatures and exposure to combustion gases that cause oxidation. Many superalloys have favorable hot corrosion resistance.

hot zones

An area that is routinely subjected to extremely high temperatures. Jet engines and steam turbines are examples of hot zones.

iron-based superalloys

A superalloy with iron as the base metal. Iron-based superalloys have high strength and corrosion resistance.

molybdenum

A hard, silvery-white metal used in superalloys to add toughness, creep strength, and wear resistance. Molybdenum is a main alloying element in many nickel-based superalloys.

nanoscale

A range measuring between one and 100 nanometers. Nanotechnology involves materials of this nanoscale size.

nickel

A hard, malleable, silvery white metal used in various alloys to add strength, toughness, and impact resistance to metals. Most superalloys are based in nickel.

nickel-based superalloys

A superalloy with nickel as the base metal. Nickel-based superalloys are the most common type of superalloy.

nitriding

A surface hardening method that heats a metal within a nitrogen-rich environment. Metals that are nitrided typically contain aluminum or chromium.

strength-to-weight ratio

The relationship between a material's strength and its weight. Materials that are light but also very strong have a high strength-to-weight ratio.

superalloy

A metal alloy consisting of numerous alloying elements that is very expensive and designed to perform under intense conditions such as elevated temperatures. Superalloys are also known as high performance alloys.

tantalum

A hard grey lustrous metallic element that is almost completely immune to any acidic substances at temperatures below 150°F. Tantalum is often used in medical implants.

thermal conductivity

A physical property that indicates how well heat energy transfers through a material. Materials with low thermal conductivity make good heat insulators.

thermal fatigue

The gradual thermal stress of a material due to temperature changes experienced over time that cause small cracks and fissures. Many superalloys exhibit a strong resistance to thermal fatigue.

toughness

The measure of a material's ability to absorb mechanical forces before fracturing. Most superalloys are tough metals.

tungsten

A dense but brittle grey metal that has the highest melting point of any pure metal. Tungsten is an exotic metal often used in light bulb filaments and gas tungsten arc welding (GTAW) electrodes.

vanadium

A hard, gray, ductile metal found in several ores and used typically as an alloy in small quantities for strengthening certain superalloys. In larger quantities, vanadium has a marked effect on hardenability and toughness.

water jet cutting

A cutting method that uses a powerful, high velocity stream of water to cut through materials. An abrasive can be added to the water to facilitate the water jet cutting process.