简介概要

Preparation of spray deposited aluminum alloy sheets via novel rolling technique

来源期刊:中国有色金属学报(英文版)2007年增刊第1期

论文作者:张昊 陈振华 严红革 陈鼎 李微

文章页码:285 - 289

Key words:aluminum alloy; ceramic rolling; spray deposition; densifying

Abstract: A novel ceramic rolling technique was developed to improve the formability of spray deposited porous aluminum alloy sheets, in which the sheet preform was canned and ceramic particulates were adopted as the medium for transferring pressure to make a homogenous hydrostatic stress field. The fractional thickness deformation, fractional longitudinal elongation, and fractional lateral spreading were calculated from the dimensions of samples before and after ceramic rolling. The results show that the flowing of metals in the longitudinal and transverse directions can be restrained during rolling. So ceramic rolling can effectively improve the density of the spray deposited performs. When the thickness reduction ratio is up to about 60%, the full density preforms can be obtained. The effect of the kinds of ceramic particulates, including Al2O3, SiO2 and graphite on the densification behavior of the preforms during rolling was investigated. The results imply that the Al2O3 particles with the size of about 74 μm are most effective.

基金信息:the Key Laboratory Open Foundation of Hunan Province, China



详情信息展示

Preparation of spray deposited aluminum alloy sheets via novel rolling technique

ZHANG Hao(张昊), CHEN Zhen-hua(陈振华), YAN Hong-ge(严红革),

CHEN Ding(陈鼎), LI Wei(李微)

College of Materials Science and Engineering, Hunan University, Changsha 410082, China

Received 15 July 2007; accepted 10 September 2007

                                                                                                                                                                

Abstract: A novel ceramic rolling technique was developed to improve the formability of spray deposited porous aluminum alloy sheets, in which the sheet preform was canned and ceramic particulates were adopted as the medium for transferring pressure to make a homogenous hydrostatic stress field. The fractional thickness deformation, fractional longitudinal elongation, and fractional lateral spreading were calculated from the dimensions of samples before and after ceramic rolling. The results show that the flowing of metals in the longitudinal and transverse directions can be restrained during rolling. So ceramic rolling can effectively improve the density of the spray deposited performs. When the thickness reduction ratio is up to about 60%, the full density preforms can be obtained. The effect of the kinds of ceramic particulates, including Al2O3, SiO2 and graphite on the densification behavior of the preforms during rolling was investigated. The results imply that the Al2O3 particles with the size of about 74 μm are most effective.

Key words: aluminum alloy; ceramic rolling; spray deposition; densifying

                                                                                                                                                                 

1 Introduction

As an advanced material preparation technology, spray deposition has been widely used to produce alloys and metal matrix composites[1-3]. In principle, the spray deposited preforms usually exhibit limited mechanical properties due to the porosity and a lack of sound metallurgical bond between the particles[4]. Higher performance can be achieved by further densification and deformation. However, comparing with the fully dense materials, the deformation of spray deposited preforms is very complicated and difficult because of the existence of porosity and oxidation film on the surface of the deposited particles.

Densification of porous metal preforms by hot working requires shearing the pores so that they collapse and the porosity is eliminated[5]. Unlike the densification of porous metal by close-die forge or extrusion via a high hydrostatic stress field, densification of porous metal during rolling occurs under a generalized stress field having both hydrostatic and deviatoric components.

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