摘要
通过硬度、差示扫描量热法(DSC)及透射电镜分析,研究了自然时效及预时效的几种6000系合金人工时效析出行为。结果表明:在170℃人工时效初期,T4态(固溶淬火后室温放置两周)合金中GP区的溶解过程推迟了β″相的析出,所形成的析出物主要是β″核心,导致时效硬化性下降;而T4P态(固溶淬火后立即170℃人工时效不同时间,然后室温放置两周)合金在这一阶段β″核心连续长大成为β″相,其显微组织以β″析出物为主,导致时效硬化性增强。增加预时效时间,人工时效硬化效果更好。对Si过剩合金,增大Mg/Si质量比,有利于β″核心的析出,提高人工时效硬化性。
By means of Vickers-hardness measurements, DSC tests and TEM analyses, the artificial aging precipitation behaviors of several 6000 alloys in natural aging and pre-aging tempers were investigated. It is indicated that GP zones＇ dissolution process of the T4 （stored for two weeks at room temperature after solution treatment） alloys in the early stages of artificial aging at 170℃ delays the precipitation of β″ phase, and the precipitates formed are mainly β″ nuclei, decreasing aging hardenability. The β″ nuclei in the T4P （immediately aged at 170℃ for different time after solution treatment and then stored for two weeks at room temperature） alloys develop into β″ phase in the same stages and the microstructure is mainly composed of β″ phase,leading to enhancement of aging hardenability. The increase of pre-aging time can obtain better hardening effect of artificial aging. For the alloy with excess Si, the increment of Mg/Si mass ratio makes for the precipitation of β″ nuclei and improves artificial aging hardenability.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2008年第4期74-78,共5页
Transactions of Materials and Heat Treatment
基金
国家"863"计划资助项目(2002AA331050)
教育部科学技术研究重大资助项目(0208)
关键词
自然时效
预时效
GP区
β″核心
时效硬化性
natural aging
pre-aging
GP zones
β″ nuclei
artificial aging hardenability
