A Study on Age-Hardening Characteristics of Squeeze Castδ- Alumina Fiber-Reinforced Al(2024) Composites.

• Main Authors: Kuo-Chan Chen, 陳國洲
• Other Authors: Chuen-Guang Chao
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/60907141904950726752

碩士 === 國立交通大學 === 材料科學(工程)研究所 === 81 === Precipitation hardening can influence the mechanical properties of the alumina-reinforced aluminum alloy(2024) composites fabricated by squeeze casting method. Owing to the presence of alumina fibers, the aging behavior of alumina reinforced aluminum alloy is different from aluminum alloy(2024) . Therefore, the condition of heat treatment for aluminum alloy (2024) is not satisfied to alumina-reinforced aluminum alloy (2024) composites. In the present study, we performed investigitions of DSC, microhardness, and observations of TEM to realize the difference of precipitation hardening processing of the two materials. It was found that the aging hardenign response of the matrix alloy in metal matrix composites caused suppression of GP zones forming. The reason is that the fiber- matrix interface can be treated as sinks of quench-in vacancies. In addition, the precipitates of aluminum alloy(2024) are GP zones and S', and that of alumina-reinfoced aluminum alloy(2024) composites is only S'. The precipitation of S' in alumima reinforced aluminum alloy(2024) composites is less than that of aluminum alloy(2024). The precipitation of S' is decreaed with increasing volume fraction of alumina fibers. Therefore, the peak hardness of the matrix of alumina- reinforced aluminum alloy (2024) composites is lower than that of aluminum alloy(2024).