Effect of in-situ formed MgO on the microstructure of thixomolded AZ91 magnesium alloy

ABSTRACT

In-situ magnesium matrix nano-composites were produced through a reaction of CO₂ with the AZ91 alloy at a semi-solid temperature range. The process was performed at 595°C, which corresponded to about 10% of solid fraction, under shear and mixing conditions generated by a screw-barrel system. As a result, nano-scale native MgO (30–50 nm) and a small amount of Al₄C₃ carbide within an eutectic consisting of α(Mg), β-Mg₁₇Al₁₂ were formed. Homogeneously distributed α(Mg) globular grains with volume 8–12% were visible. AZ91 composites revealed yield strength of 220 MPa at compression strength of 460 MPa and hardness 103 ± 2 HV.

KEYWORDS:

• MgO – in-situ
• thixomolding
• magnesium base composites
• HRTEM

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors gratefully acknowledge the financial support of the National Centre for Research and Development, Grant No.: LIDER/007/151/L-5/13/NCBR/2014.