Paper Title:
Shear Enhanced Heterogeneous Nucleation in AZ91D Alloy
  Abstract

Intensive shearing was applied to AZ91D Mg-alloy melts at temperatures above its liquidus (600oC) by using a twin-screw mechanism. The sheared melt was then cast into a TP1 mould (Aluminium Association’s standard test mould with 3.5K/s cooling rate) for microstructural examination. Alloy melts, both with and without shearing, were also filtered using a pressurized filtration technique to collect oxides and other second phase particles. The experimental results showed a significant grain refinement of AZ91D alloy through enhancement of heterogeneous nucleation. Based on the experimental results, a multi-step heterogeneous nucleation mechanism has been proposed: (1) intensive melt shearing converts oxide films and clusters into fine and well-dispersed particles with a narrow size distribution; (2) the dispersed oxide particles act as potent sites for nucleation of Al8Mn5 intermetallic particles; (3) during the further cooling, Al8Mn5 intermetallic particles nucleate the -Mg phase, resulting in a fine and uniform microstructure. The proposed multi-step nucleation mechanism will be discussed in terms of the effect of forced wetting, particle size and particle size distribution on the enhancement of heterogeneous nucleation.

  Info
Periodical
Edited by
A. Roósz, V. Mertinger, P. Barkóczy and Cs. Hoó
Pages
301-306
DOI
10.4028/www.scientific.net/MSF.649.301
Citation
Z. Fan, M. Xia, Y. Wang, S. Arumuganathar, G. M. Scamans, "Shear Enhanced Heterogeneous Nucleation in AZ91D Alloy", Materials Science Forum, Vol. 649, pp. 301-306, 2010
Online since
May 2010
Export
Price
$32.00
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: Yukio Kato, Yuichi Nakamura, Kenji Murata, Kouhei Inoue, Shigeru Itoh
475
Authors: Jin Yong Zhang, Zheng Yi Fu, Wei Min Wang, Qing Jie Zhang
Abstract:Recently research shows that heterogeneous model is needed to explain some complex combustion behaviors in SHS. However, more heterogeneous...
3259
Authors: Cheng Huang, Bo Song, Pei Zhao
Abstract:In this paper, the thermodynamic and kinetic requirements of heterogeneous and homogeneous nucleation of metallic melting were suggested....
1941
Authors: Hidenori Terasaki, Tomonori Yamada, Yuichi Komizo
Abstract:Heterogeneous nucleation and growth of acicular ferrite in HSLA steel weld-metal were in-situ observed by using laser scanning confocal...
33
Authors: Ying Wu Wang, Xiao Qing Zuo, Jian Sheng Lu, Yun Zhou
Materials Engineering
Abstract:Being the first step of foaming, bubble heterogeneous nucleation of aluminum foam has remarkable effects on the final cell structure of...
1682