The influence of reinforced particle fracture on strengthening of spray formed Cu-TiB2 composite

There have been several efforts to develop high strength copper alloys while maintaining a good conductivity, especially at elevated temperatures. High strength/high conductivity Cu alloys can be achieved by reinforcing or dispersing ceramic particles such as oxides, borides, carbides, and nitrides in the Cu matrix. The TiB{sub 2} particle, among others, is a potential candidate for reinforcement of the Cu alloy because of its high melting point (3225 C), hardness (3400kg/mm{sup 2}), and thermal conductivity (66W/mK). The thermal stability of dispersion-strengthened (DS) Cu alloys is generally superior to that of precipitation-hardened alloys. The dispersion strengthening of a Cu alloy has been convention ally produced by the powder metallurgical process using internal oxidation or mechanical alloying. These methods showed minor success due to the limitation in reinforcing volume fraction and contamination problems. An alternative method to manufacture DS Cu alloy is the spray forming process, which is not only free from such problems but also economically viable. The purpose of this study, therefore, is to analyze the strengthening mechanism of a Cu-TiB{sub 2} particulate composite using dislocation pile-up model, which is often represented by the Hall-Petch relationship. This model considers the effect of the interaction of reinforced particles and dislocations. Particularmore » emphasis has been placed on the effect of reinforcement fracture on the strengthening which occurs during deformation of the composite.« less