Precipitation and strengthening in selected magnesium alloys

Research output: Contribution to conferencePaperOther

6 Citations (Scopus)

Abstract

Recent results of the characterisation of strengthening precipitate phases in magnesium alloys WE54 and AZ91 using transmission electron microscopy, identification of the formation mechanisms of the strengthening phases, and modelling of quantitative effects of the size, orientation and distribution of such phases on strengthening are reviewed. The key strengthening precipitate phase appears to be an intermediate phase Mg3(Nd,Y), which forms as plates parallel to {11̄00}α, in alloy WE54, and the equilibrium phase Mg17Al12 that forms as (0001)α laths, in AZ91. The formation of both precipitate phases generates significant shear strain energy, and a potential mechanism to accommodate the shear strain energy involves nucleation of such phases in association with clusters of larger solute atoms and vacancies. The model that emerges suggests that, to increase the number density of precipitates of Mg3(Nd, Y) or Mg17Al12, the potential microalloying elements should have atomic sizes larger than Mg and have high binding energies with vacancies. Results of modelling indicate that, for a given volume fraction and number density of precipitates which are either shearable or shear-resistant, the yield strength increment produced by precipitate plates formed on prismatic planes of the matrix phase is significantly larger than that produced by precipitate plates formed on the basal plane of the matrix phase, and increases substantially with an increase in plate aspect ratio.

Original languageEnglish
Pages103-110
Number of pages8
Publication statusPublished - 1 Jan 2002
EventMagnesium Technology 2002 - Seattle, WA, United States of America
Duration: 17 Feb 200221 Feb 2002

Conference

ConferenceMagnesium Technology 2002
CountryUnited States of America
CitySeattle, WA
Period17/02/0221/02/02

Cite this

Nie, J. F. (2002). Precipitation and strengthening in selected magnesium alloys. 103-110. Paper presented at Magnesium Technology 2002, Seattle, WA, United States of America.
Nie, J. F. / Precipitation and strengthening in selected magnesium alloys. Paper presented at Magnesium Technology 2002, Seattle, WA, United States of America.8 p.
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Nie, JF 2002, 'Precipitation and strengthening in selected magnesium alloys' Paper presented at Magnesium Technology 2002, Seattle, WA, United States of America, 17/02/02 - 21/02/02, pp. 103-110.

Precipitation and strengthening in selected magnesium alloys. / Nie, J. F.

2002. 103-110 Paper presented at Magnesium Technology 2002, Seattle, WA, United States of America.

Research output: Contribution to conferencePaperOther

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N2 - Recent results of the characterisation of strengthening precipitate phases in magnesium alloys WE54 and AZ91 using transmission electron microscopy, identification of the formation mechanisms of the strengthening phases, and modelling of quantitative effects of the size, orientation and distribution of such phases on strengthening are reviewed. The key strengthening precipitate phase appears to be an intermediate phase Mg3(Nd,Y), which forms as plates parallel to {11̄00}α, in alloy WE54, and the equilibrium phase Mg17Al12 that forms as (0001)α laths, in AZ91. The formation of both precipitate phases generates significant shear strain energy, and a potential mechanism to accommodate the shear strain energy involves nucleation of such phases in association with clusters of larger solute atoms and vacancies. The model that emerges suggests that, to increase the number density of precipitates of Mg3(Nd, Y) or Mg17Al12, the potential microalloying elements should have atomic sizes larger than Mg and have high binding energies with vacancies. Results of modelling indicate that, for a given volume fraction and number density of precipitates which are either shearable or shear-resistant, the yield strength increment produced by precipitate plates formed on prismatic planes of the matrix phase is significantly larger than that produced by precipitate plates formed on the basal plane of the matrix phase, and increases substantially with an increase in plate aspect ratio.

AB - Recent results of the characterisation of strengthening precipitate phases in magnesium alloys WE54 and AZ91 using transmission electron microscopy, identification of the formation mechanisms of the strengthening phases, and modelling of quantitative effects of the size, orientation and distribution of such phases on strengthening are reviewed. The key strengthening precipitate phase appears to be an intermediate phase Mg3(Nd,Y), which forms as plates parallel to {11̄00}α, in alloy WE54, and the equilibrium phase Mg17Al12 that forms as (0001)α laths, in AZ91. The formation of both precipitate phases generates significant shear strain energy, and a potential mechanism to accommodate the shear strain energy involves nucleation of such phases in association with clusters of larger solute atoms and vacancies. The model that emerges suggests that, to increase the number density of precipitates of Mg3(Nd, Y) or Mg17Al12, the potential microalloying elements should have atomic sizes larger than Mg and have high binding energies with vacancies. Results of modelling indicate that, for a given volume fraction and number density of precipitates which are either shearable or shear-resistant, the yield strength increment produced by precipitate plates formed on prismatic planes of the matrix phase is significantly larger than that produced by precipitate plates formed on the basal plane of the matrix phase, and increases substantially with an increase in plate aspect ratio.

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Nie JF. Precipitation and strengthening in selected magnesium alloys. 2002. Paper presented at Magnesium Technology 2002, Seattle, WA, United States of America.