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Improvement of high temperature strength of MA Al and Cu P/M materials by directional annealing

定向退火提高MA Al和Cu P/M材料的高温强度

基本信息

批准号：
04650634
负责人：
KANEKO Junichi
金额：
$ 1.47万
依托单位：
Nihon University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

By hot extrusion, fine grained microstructures are generally formed in the matrix of mechanically alloyed P/M aluminum materiaaaaaaaaals and whisker reinforced aluminum alloy composites. in such cases, tensile strength decreases and elongation increases markedly at high temperatures due to increased contribution of grain grain boundary sliding. Superplasticity is observed in the extreme. Although such properties are suitable for hot working of these advanced mateerials, much higher strength at elevated temperates is desirable at their end uses. in this work, directional annealing was applied to MA P/M aluminum materials and SiC/6061 extruded composites for the purpose of attaining improved high temperature strength by causing grain coarsening of the matrix.No appreciable grain coarsening of the matrix was observed in directional annealing of MA P/M aluminum materials, in which the fine graind structure was stabilized by finely dispersed particles introduced by MA.However, directional annealing at 873K for 5h caused appreciable softening of SiCw/6061 extruded composites. the pole figures showed the <111> texture of the 6061 alloy matrix for both as-extruded and directionally annealed materials. The obtaind pole figures of the annealed materials obviously showed coarse grain structures of the matrix. At 673K, the directionally annealed materials showed higher tensile strength than as-extruded ones. However, tensile strengt at room temperature is decreased by 50 to 100 MPa by applying directional annealing. Thus, fine grain and subgrain structures of the matrix formed by hot extrusion are contributing to an appreciable strength increment of the composites at room temperature. In conclusion, directional annealing of SiCw/6061 extruded composites can give improved high-temperature strength at the sacrifice of room-teemperature strength.

机械合金化铝合金材料和晶须增强铝合金复合材料经热挤压后，基体中普遍形成细晶组织。在这种情况下，由于晶界滑动的贡献增加，在高温下抗拉强度降低，伸长率显著增加。超塑性是在极端情况下观察到的。虽然这些性能适合于这些先进材料的热加工，但在其最终用途中，需要在高温下具有更高的强度。本文对MA粉末冶金铝合金材料和SiC/6061挤压复合材料进行了定向退火处理，目的是通过使基体晶粒粗化来提高材料的高温强度。在MA粉末冶金铝合金材料的定向退火处理中，没有观察到明显的基体晶粒粗化，因为MA粉末冶金引入的细小弥散颗粒稳定了细晶组织。然而，在873 K下定向退火5 h，SiCw/6061复合材料发生了明显的软化。极图显示<111>了6061合金基体对于挤压态和定向退火材料的织构。热处理后材料的极图显示出明显的基体粗晶组织。在673 K时，定向退火材料的拉伸强度比挤压态的高。而定向退火使室温拉伸强度降低50 ~ 100 MPa。因此，细晶和亚晶组织的热挤压形成的基体是有助于在室温下的复合材料的强度增加可观。总之，定向退火可以在牺牲室温强度的基础上提高SiCw/6061挤压复合材料的高温强度。