Metallurgical and Materials Transactions A

, Volume 42, Issue 7, pp 1950-1959

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Grain Size Hardening in Mg and Mg-Zn Solid Solutions

  • C. H. CaceresAffiliated withARC Centre of Excellence for Design in Light Metals, Materials Engineering, School of Engineering, The University of Queensland Email author 
  • , Gemma E. MannAffiliated withCAST Co-operative Research Centre, Materials Engineering, School of Engineering, The University of QueenslandCentral Queensland University
  • , J. R. GriffithsAffiliated withCSIRO Process Science and Engineering


Cast specimens of Mg and of several Mg-Zn binary alloys with a wide range of grain sizes were deformed in tension and compression. The k values calculated from the Hall–Petch (H-P) plots of the tensile 0.2 pct proof stress increased with the Zn content, from 0.24 MPa m1/2 for pure Mg to ~0.66 MPa m1/2 for the 2.3 at. pct Zn alloy; k values measured from compression tests were larger, typically by 0.05 MPa m1/2. When the strength measurements were corrected for the pseudoelastic strain resulting from elastic twinning, the k values generally increased, and the difference between tension and compression was eliminated. This showed that the larger k values obtained in compression using uncorrected data were an artifact of the pseudoelastic effect. The apparent friction stress varied between about 14 MPa for pure Mg to very low or negative values for the most dilute alloy, increasing again to about 8 MPa for the most concentrated alloy. The use of strength data corrected for pseudoelasticity effects is necessary for a consistent analysis of the grain size hardening.