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Title: Investigation of precipitate refinement in Mg alloys by an analytical composite failure model

Abstract

An analytical model is developed to simulate precipitate refinement in second phase strengthened magnesium alloys. The model is developed based on determination of the stress fields inside elliptical precipitates embedded in a rate dependent inelastic matrix. The stress fields are utilized to determine the failure mode that governs the refinement behavior. Using an AZ31 Mg alloy as an example, the effects the applied load, aspect ratio and orientation of the particle is studied on the macroscopic failure of a single α-Mg17Al12 precipitate. Additionally, a temperature dependent version of the corresponding constitutive law is used to incorporate the effects of temperature. In plane strain compression, an extensional failure mode always fragments the precipitates. The critical strain rate at which the precipitates start to fail strongly depends on the orientation of the precipitate with respect to loading direction. The results show that the higher the aspect ratio is, the easier the precipitate fractures. Precipitate shape is another factor influencing the failure response. In contrast to elliptical precipitates with high aspect ratio, spherical precipitates are strongly resistant to sectioning. In pure shear loading, in addition to the extensional mode of precipitate failure, a shearing mode may get activated depending on orientation and aspectmore » ratio of the precipitate. The effect of temperature in relation to strain rate was also verified for plane strain compression and pure shear loading cases.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1332626
Report Number(s):
PNNL-SA-114910
Journal ID: ISSN 0167-6636; VT0505000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Mechanics of Materials
Additional Journal Information:
Journal Volume: 89; Journal ID: ISSN 0167-6636
Publisher:
Elsevier
Country of Publication:
United States
Language:
English

Citation Formats

Tabei, Ali, Li, Dongsheng, Lavender, Curt A., and Garmestani, Hamid. Investigation of precipitate refinement in Mg alloys by an analytical composite failure model. United States: N. p., 2015. Web. doi:10.1016/j.mechmat.2015.05.007.
Tabei, Ali, Li, Dongsheng, Lavender, Curt A., & Garmestani, Hamid. Investigation of precipitate refinement in Mg alloys by an analytical composite failure model. United States. doi:10.1016/j.mechmat.2015.05.007.
Tabei, Ali, Li, Dongsheng, Lavender, Curt A., and Garmestani, Hamid. Thu . "Investigation of precipitate refinement in Mg alloys by an analytical composite failure model". United States. doi:10.1016/j.mechmat.2015.05.007.
@article{osti_1332626,
title = {Investigation of precipitate refinement in Mg alloys by an analytical composite failure model},
author = {Tabei, Ali and Li, Dongsheng and Lavender, Curt A. and Garmestani, Hamid},
abstractNote = {An analytical model is developed to simulate precipitate refinement in second phase strengthened magnesium alloys. The model is developed based on determination of the stress fields inside elliptical precipitates embedded in a rate dependent inelastic matrix. The stress fields are utilized to determine the failure mode that governs the refinement behavior. Using an AZ31 Mg alloy as an example, the effects the applied load, aspect ratio and orientation of the particle is studied on the macroscopic failure of a single α-Mg17Al12 precipitate. Additionally, a temperature dependent version of the corresponding constitutive law is used to incorporate the effects of temperature. In plane strain compression, an extensional failure mode always fragments the precipitates. The critical strain rate at which the precipitates start to fail strongly depends on the orientation of the precipitate with respect to loading direction. The results show that the higher the aspect ratio is, the easier the precipitate fractures. Precipitate shape is another factor influencing the failure response. In contrast to elliptical precipitates with high aspect ratio, spherical precipitates are strongly resistant to sectioning. In pure shear loading, in addition to the extensional mode of precipitate failure, a shearing mode may get activated depending on orientation and aspect ratio of the precipitate. The effect of temperature in relation to strain rate was also verified for plane strain compression and pure shear loading cases.},
doi = {10.1016/j.mechmat.2015.05.007},
journal = {Mechanics of Materials},
issn = {0167-6636},
number = ,
volume = 89,
place = {United States},
year = {2015},
month = {10}
}