What is a key feature of parts created using powder metallurgy techniques?

The key feature of parts created using powder metallurgy techniques is that they are often very porous. This porosity results from the powder being compacted and then sintered at high temperatures. During the sintering process, particles fuse together, leading to a structure that can retain pores. These pores can be beneficial in certain applications, such as filtration or lubrication, where the material can hold fluids or act as a passage for gases.

The ability to control the porosity by adjusting the compaction and sintering process gives powder metallurgy a distinct advantage for producing specialized components. This characteristic is associated with the material's microstructure and significantly influences its mechanical properties, such as strength, ductility, and thermal conductivity.

The other options do not accurately represent a defining feature of powder metallurgy. Parts created using this technique can indeed be shaped during the compaction phase, and they can be further processed or finished after sintering. Additionally, while some materials may be subject to degradation, it is not a universal characteristic of powder metallurgy parts.