Strengthening effects in precipitation and dispersion hardened powder metallurgy copper alloys

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• 作者：J. Ru?i? ^{jruzic@vinca.rs} ; J. Sta&scaron ; i? ; ^{jelsta@vinca.rs} ; V. Rajkovi? ^{visnja@vinca.rs} ; D. Bo?i? ^{dbozic@vinca.rs}
• 关键词：Copper alloy ; Precipitation hardening ; Dispersion hardening ; Multiple hardening ; Hardness testing
• 刊名：Materials and Design
• 出版年：2013
• 出版时间：August, 2013
• 年：2013
• 卷：49
• 期：Complete
• 页码：746-754
• 全文大小：3752 K

文摘

The hardening of copper and copper alloy matrix using powder metallurgy (PM) techniques and different ways for dispersoids formation, as well as analysis of their single and combined effects on the strength of obtained material at room and elevated temperatures, have been presented and discussed. Gas atomized Cu-3.8 wt. % Ti and Cu-0.6 wt. % Ti-2.5 wt. % TiB₂ (Cu-Ti-TiB₂) powders and mechanically alloyed powder Cu-4 wt. % TiB₂ were used as starting materials. The powders were consolidated by hot isostatic pressing (HIP) and hot pressing (HP). Optical, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX), as well as transmission electron microscope (TEM) were used for microstructure characterization of the compacts. High strengthening of the Cu-Ti compacts was achieved by thermal treatment (aging) as a consequence of the development of modular structure and precipitation of metastable Cu₄Ti_(m). Hardening in the Cu-Ti-TiB₂ compacts is due to simultaneous influence of the following factors: the development of modular structure, precipitation of metastable Cu₄Ti_(m), and the presence of TiB₂ dispersoid nanoparticles. In case of Cu-TiB₂ compacts, high starting values of hardness and hardness on the elevated temperatures result from the presence of finely distributed TiB₂ particles in copper matrix obtained by mechanical alloying. Cu-Ti-TiB₂ composite yields much higher hardness values compared with the binary Cu-Ti alloys, owing to primary TiB₂ dispersions formed during atomization. Separation of metastable Cu₄Ti precipitate and the presence of significantly finer TiB₂ particles in the copper matrix are the reason for higher hardness values at peak temperatures (400-500 ¡ãC) in multiple-hardened copper alloy compared to the dispersion-hardened.