Role of applied uniaxial stress during creep testing on precipitation in Mg-Nd alloys

Deep Choudhuri; Nilesh Dendge; Soumya Nag; Mark A. Gibson; Rajarshi Banerjee

doi:10.1016/j.msea.2014.06.035

Role of applied uniaxial stress during creep testing on precipitation in Mg-Nd alloys

Deep Choudhuri, Nilesh Dendge, Soumya Nag, Mark A. Gibson, Rajarshi Banerjee

Research output: Contribution to journal › Article › peer-review

23 Scopus citations

Abstract

The coupled effects of an applied stress and temperature, during creep testing at 90MPa/177°C, on intragranular second phase (orthorhombic β' and fcc β₁ phases) precipitation in a binary Mg-0.5at% Nd alloy were investigated by comparing and contrasting with second phase precipitation under isothermal (177°C) annealing conditions. In the early stages of creep deformation, after 5h, homogeneous precipitation of fine scale β' was observed within the α-Mg matrix, while on the other hand, only small pockets of Nd enrichment were observed in the isothermally annealed sample after 5h, indicating that β' precipitation is accelerated during creep testing. With respect to β₁ precipitation, these precipitates appeared to decorate dislocation lines primarily, which is indicative of a dislocation stress-field assisted precipitation mechanism, in both creep tested and isothermally annealed samples. Interestingly, the β₁ precipitates appear to grow and coarsen more rapidly in the case of the isothermally annealed sample than in the creep tested sample. The differences between the precipitation behavior of β' and β₁ phases under the influence of stress and temperature (creep testing) vs. only under isothermal annealing conditions have been rationalized based on the crystal structures of these phases and their elastic interaction energies with the stress-fields associated with dislocations as well as bulk applied stress.

Original language	English
Pages (from-to)	140-152
Number of pages	13
Journal	Materials Science and Engineering: A
Volume	612
DOIs	https://doi.org/10.1016/j.msea.2014.06.035
State	Published - Aug 26 2014
Externally published	Yes

Funding

The authors gratefully acknowledge the Center for Advanced Research and Technology (CART) at the University of North Texas. CAST Cooperative Research Centre (CAST CRC) was established under, and is supported in part by, the Australian Government’s Cooperative Research Centres scheme. MAG would like to acknowledge the technical assistance of Mrs. M. Gershenzon and Mr. A. Yob in the HPDC of the samples used in this work. The authors would also like to thank Yipeng Gao and Prof Yunzhi Wang from The Ohio State University for helpful discussions regarding the calculation of stress free transformation strains.

Funders	Funder number
Australian Government’s Cooperative Research Centres scheme

Keywords

Creep
Elastic interaction energy
Magnesium alloy
Precipitation
Rare-earth element

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title = "Role of applied uniaxial stress during creep testing on precipitation in Mg-Nd alloys",

abstract = "The coupled effects of an applied stress and temperature, during creep testing at 90MPa/177°C, on intragranular second phase (orthorhombic β' and fcc β1 phases) precipitation in a binary Mg-0.5at% Nd alloy were investigated by comparing and contrasting with second phase precipitation under isothermal (177°C) annealing conditions. In the early stages of creep deformation, after 5h, homogeneous precipitation of fine scale β' was observed within the α-Mg matrix, while on the other hand, only small pockets of Nd enrichment were observed in the isothermally annealed sample after 5h, indicating that β' precipitation is accelerated during creep testing. With respect to β1 precipitation, these precipitates appeared to decorate dislocation lines primarily, which is indicative of a dislocation stress-field assisted precipitation mechanism, in both creep tested and isothermally annealed samples. Interestingly, the β1 precipitates appear to grow and coarsen more rapidly in the case of the isothermally annealed sample than in the creep tested sample. The differences between the precipitation behavior of β' and β1 phases under the influence of stress and temperature (creep testing) vs. only under isothermal annealing conditions have been rationalized based on the crystal structures of these phases and their elastic interaction energies with the stress-fields associated with dislocations as well as bulk applied stress.",

keywords = "Creep, Elastic interaction energy, Magnesium alloy, Precipitation, Rare-earth element",

author = "Deep Choudhuri and Nilesh Dendge and Soumya Nag and Gibson, {Mark A.} and Rajarshi Banerjee",

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AU - Choudhuri, Deep

AU - Dendge, Nilesh

AU - Nag, Soumya

AU - Gibson, Mark A.

AU - Banerjee, Rajarshi

PY - 2014/8/26

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N2 - The coupled effects of an applied stress and temperature, during creep testing at 90MPa/177°C, on intragranular second phase (orthorhombic β' and fcc β1 phases) precipitation in a binary Mg-0.5at% Nd alloy were investigated by comparing and contrasting with second phase precipitation under isothermal (177°C) annealing conditions. In the early stages of creep deformation, after 5h, homogeneous precipitation of fine scale β' was observed within the α-Mg matrix, while on the other hand, only small pockets of Nd enrichment were observed in the isothermally annealed sample after 5h, indicating that β' precipitation is accelerated during creep testing. With respect to β1 precipitation, these precipitates appeared to decorate dislocation lines primarily, which is indicative of a dislocation stress-field assisted precipitation mechanism, in both creep tested and isothermally annealed samples. Interestingly, the β1 precipitates appear to grow and coarsen more rapidly in the case of the isothermally annealed sample than in the creep tested sample. The differences between the precipitation behavior of β' and β1 phases under the influence of stress and temperature (creep testing) vs. only under isothermal annealing conditions have been rationalized based on the crystal structures of these phases and their elastic interaction energies with the stress-fields associated with dislocations as well as bulk applied stress.

AB - The coupled effects of an applied stress and temperature, during creep testing at 90MPa/177°C, on intragranular second phase (orthorhombic β' and fcc β1 phases) precipitation in a binary Mg-0.5at% Nd alloy were investigated by comparing and contrasting with second phase precipitation under isothermal (177°C) annealing conditions. In the early stages of creep deformation, after 5h, homogeneous precipitation of fine scale β' was observed within the α-Mg matrix, while on the other hand, only small pockets of Nd enrichment were observed in the isothermally annealed sample after 5h, indicating that β' precipitation is accelerated during creep testing. With respect to β1 precipitation, these precipitates appeared to decorate dislocation lines primarily, which is indicative of a dislocation stress-field assisted precipitation mechanism, in both creep tested and isothermally annealed samples. Interestingly, the β1 precipitates appear to grow and coarsen more rapidly in the case of the isothermally annealed sample than in the creep tested sample. The differences between the precipitation behavior of β' and β1 phases under the influence of stress and temperature (creep testing) vs. only under isothermal annealing conditions have been rationalized based on the crystal structures of these phases and their elastic interaction energies with the stress-fields associated with dislocations as well as bulk applied stress.

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Role of applied uniaxial stress during creep testing on precipitation in Mg-Nd alloys

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Keywords

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