Microstructures and Mechanical Properties of ZK60-XHo Wrought Magnesium Alloys

Abstract:

Microstructures and phase compositions of as-cast and extruded ZK60-xHo (x=0~5) alloys were analyzed by X-ray diffraction, differential scanning calorimetry, optical microscope, scanning electron microscope and transmission electron microscope. Meanwhile, tensile mechanical property and impact toughness were tested. The results showed that as-cast microstructure was refined gradually with increasing the Ho content. Mg-Zn-Ho new phase increased gradually, while MgZn₂ phase reduced gradually to disappear. Second phase tended to distribute along grain boundary by continuous network. As-cast tensile mechanical property remained almost unchanged and impact toughness value α_nK was low (9~17 J/cm²). After extrusion by λ=40/T=593 K, grain size reached the micron level (1~5 μm) and broken second phase distributed dispersedly. Extruded tensile mechanical property was enhanced obviously. Tensile strength σ_b at ambient temperature increased gradually from 355 MPa for ZK60 alloy to 375 MPa for ZK60-4.77Ho alloy, while elongation δ decreased gradually from 19.5% to 12.5%. σ_b at 473 K increased gradually from 120 MPa to 169 MPa. Meanwhile, α_nK was enhanced to 26~54 J/cm². Fine grain and few fine dispersed second phase enhanced the tensile mechanical property and impacted toughness of magnesium alloys effectively.

• Periodical: Materials Science Forum (Volumes 747-748)
• Pages: 359-368
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.747-748.359
• Online since: February 2013
• Authors: Zheng Hua Huang, Wen Jun Qi, Jing Xu
• Keywords: Ho Modification, Mechanical Property, Microstructure, Wrought Magnesium Alloys, ZK60 Alloy

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