Shear flow characteristics and crystallization kinetics during steady non-isothermal flow of Vitreloy-1

被引：31

作者：

Demetriou, MD ^{[1
]}

Johnson, WL ^{[1
]}

机构：

[1] CALTECH, Keck Lab Engn Mat, Dept Mat Sci, Pasadena, CA 91125 USA

来源：

ACTA MATERIALIA | 2004年 / 52卷 / 12期

关键词：

finite element analysis; bulk metallic glasses; crystallization kinetics; continuous extrusion; shear thinning;

D O I：

10.1016/j.actamat.2004.03.034

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

The steady non-isothermal channel flow of Vitreloy-1 (Zr41.25Ti13.75Cu12.5Ni10Be22.5)is simulated by means of finite element modeling. Non-Newtonian flow behavior is accounted for by employing a self-consistent shear-rate dependent flow law. Transition to non-Newtonian flow and shear localization is obtained by superimposing the computed flow evolution onto an experimentally developed flow diagram. The coordinate points that mark transition to shear localization form a narrow boundary layer similar to23%, of the channel thickness. The deformation-induced enhancement of crystallization kinetics is approximately accounted for by utilizing the shear-rate dependent viscosity law to shift the transformation time in the apparent TTT diagram. The kinetics of crystallization during flow are assessed by superimposing the temperature evolution onto the "shifted" TTT diagram. The coordinate points that mark the onset of crystallization form a boundary layer similar to15% of the channel thickness, which are narrower than the shear localization boundary layer suggesting that crystallites will form in the shear-banded region. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：3403 / 3412

页数：10

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