Microforming of Bulk Metallic Glasses: Constitutive Modelling and Applications

Abstract

Microforming can be a good application for bulk metallic glasses. It is important to simulate the deformation behaviour of the bulk metallic glasses in a supercooled liquid region for manufacturing micromachine parts. For these purposes, a correct constitutive model which can reproduce viscosity results is essential for good predicting capability. In this paper, we studied deformation behaviour of the bulk metallic glasses using the finite element method in conjunction with the fictive stress constitutive model which can describe non-Newtonian as well as Newtonian behaviour. A combination of kinetic equation which describes the mechanical response of the bulk metallic glasses at a given temperature and evolution equations for internal variables provide the constitutive equation of the fictive stress model. The internal variables are associated with fictive stress and relation time. The model has a modular structure and can be adjusted to describe a particular type of microforming process. Implementation of the model into the MARC software has shown its versatility and good predictive capability.

Strain rate dependent shear banding behavior of a Zr-based bulk metallic glass composite

“…The shear modulus is 22.7 GPa, the compressive yield strength is 550 MPa and 6500 kg/m 3 for the density. Here, we take the order of the G for 10 10 Pa, τ y for 10 8 Pa, ρ for 10 3 kg/m 3 . Otherwise, the parameters of 11 kinds of general crystalline alloys were given in Grady's work [44].…”

“…Bulk metallic glasses (BMGs) have attracted large interests due to their unique mechanical and physical properties [1][2][3][4][5][6], showing widespread potential applications [7][8][9][10][11]. However, this is impeded by the poor room-temperature plasticity, which results from the easy nucleation and fast propagation of shear band in this type of amorphous materials [12][13][14][15][16][17][18].…”

Coupled thermo-mechanical modelling of bulk-metallic glasses: Theory, finite-element simulations and experimental verification

“…Recently, Anand and Su (2005) and Yang et al (2006) have formulated an isothermal, three-dimensional finitedeformation-based model for metallic glasses. 1 Another class of model which has been used to study the deformation behavior of metallic glasses is the fictive stress-based constitutive model (Kato et al, 2000;Lu et al, 2003;Kim et al, 2004).…”

The multi-axial deformation behavior of bulk metallic glasses at high homologous temperatures

“…and Saotome et al (2001) have studied the superplastic deformation of an La-based metallic glass in the supercooled liquid region. The micro-forming ability of Zr-based BMGs have also been investigated by , Kim et al (2004), Wang et al (2005) and Lewandowski et al (2006. Recently, Schroers (2008) has also studied the formability of a variety of BMGs within their respective supercooled liquid region.…”

“…Huang et al (2002) have developed a three-dimensional and small-strain-based constitutive model for metallic glasses. A fictive-stress-based theory was used by Kim et al (2004) to model the micro-forming process of a BMG within the supercooled liquid region. 1 0020-7683/$ -see front matter Ó 2009 Elsevier Ltd. All rights reserved.…”