Powder Metallurgy High-temperature Alloys
Powder metallurgy (PM) is a process used to produce high-temperature alloys. The powder is produced from metal powders which are then compacted into a predetermined shape and sintered, or heated to produce a homogenous product. High-temperature alloys are alloys used in applications where temperatures exceed 600°C (1110°F). These types of alloys are typically used for aerospace components such as turbine blades, and for automotive parts such as exhaust manifolds, gaskets and springs.
The use of PM to manufacture high-temperature alloys has become increasingly popular because of its unique advantages over more traditional alloy-manufacturing processes. With PM, the alloy shape is formed in the powder form at ambient conditions, rather than in a molten state. This eliminates the need for additional energy and processing to form the alloy into the desired shapes. Additionally, the sintering temperatures required to form a high-temperature alloy are much lower than those required to form a forged or cast alloy. This allows for the manufacture of high-temperature alloys at a lower cost.
High-temperature alloys manufactured using PM typically have a higher strength-to-weight ratio than those produced using traditional manufacturing techniques. In addition, these alloys typically have an improved resistance to fatigue and creep. Another advantage is that the mechanical properties of PM alloys can be tailored to meet specific application requirements. For example, alloy-composition can be altered with respect to the amount of carbon, chromium and molybdenum present to achieve different characteristics.
In order to manufacture high-temperature alloys using PM, the powder particles must be of appropriate size and shape to achieve a high degree of compaction. Additionally, the powder needs to be conducive to forming a homogenous structure. Alloys with higher melting points require higher pressure to achieve a level of compaction that allow for a homogenous structure. Special additives, including sintering aids and lubricants, may also be added to the powder to facilitate the compaction process. Once the powder is compacted and sintered, the alloy is ready for use.
PM continues to be a popular manufacturing technique for high-temperature alloys for its numerous advantages, including reduced energy and processing costs, improved strength-to-weight ratio, increased fatigue and creep resistance and tailored mechanical properties. PM can also be used to manufacture alloys with higher melting points by increasing the compaction pressure.
