Jia She

Development of magnesium-graphene nanoplatelets composite

In recent years, graphene has attracted a great research interest in all fields of sciences due to its unique properties. Its excellent mechanical properties lead it to be used in nanocomposites for strength enhancement. In current work, a new magnesium-graphene nanoplatelets composite is fabricated for the first time using semi-powder metallurgy method. The effect of graphene nanoplatelets addition on the mechanical behaviour of pure magnesium under both tension and hardness is investigated. The results demonstrate that graphene nanoplatelets are distributed homogeneously in the magnesium matrix, therefore act as an effective reinforcing filler to prevent the deformation. Compared to monolithic magnesium, the magnesium/0.3 wt% graphene nanoplatelets composite exhibited improved elastic modulus, yield strength, ultimate tensile strength and Vickers hardness. The improvement in elastic modulus, yield strength (0.2%), ultimate tensile strength and Vickers hardness for magnesium/0.3 wt% graphene nanoplatelets composite relative to pure magnesium are up to +10.6%, +5%, +8% and +19.3%, respectively. In addition to tensile and hardness tests for the analysis of mechanical properties of as synthesized composite, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction are used to investigate the surface morphology, elemental percentage composition and phase analysis, respectively.

High conductivity and high strength Mg–Zn–Cu alloy

Abstract In the present work, electrical conductivity (EC) and Vickers hardness of Mg–Zn–xCu (x = 0, 0·5, 1·0 and 1·5) alloys in as cast, as solution and aged states have been investigated. The result shows that the EC of both as cast and as solution samples increases with Cu content, and Cu addition would have remarkably enhanced effect on EC and age hardening response during subsequent aging treatment. The 1·0Cu alloy aged at 160°C for 16 h after solution treatment had the optimal combined properties of high microhardness (94 HV) and high EC value (19·1, 106 S m−1), noting that the EC of pure Mg is 22·8 (106 S m−1). It is believed that the accelerated precipitation process for Cu containing alloy is attributed to the favourable interactions between Zn, Cu and vacancies. The microstructure associated with the improvement of EC and microhardness for Cu containing alloy is also discussed in detail.

Microstructure and mechanical properties of asextruded Mg–xAl–5Sn–0·3Mn alloys (x = 1, 3, 6 and 9)

Abstract Properties of Mg–xAl–5Sn–0·3Mn alloys (x = 1, 3, 6 and 9) prepared by hot extrusion are reported. The orientation relationship between Mg2Sn precipitate and Mg matrix in Mg–9Al–5Sn–0·3Mn alloy was determined. The yield strength of the as extruded alloys initially decreased with increasing Al content, then increased for Al contents >6 wt-%. These changes are interpreted in terms of the effect of texture, grain size and second phase on the yield strength of the alloys.

Influence of Sn addition on mechanical properties of gas tungsten arc welded AM60 Mg alloy sheets

Abstract The effects of Sn addition on the microstructure and mechanical properties of gas tungsten arc butt-welded Mg–6Al– 0.3Mn (AM60) (mass fraction, %) alloy sheets were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and microhardness and tensile tests. The results indicate that both the average microhardness and joint efficiency of AM60 are improved by the addition of 1% Sn (mass fraction). The ultimate tensile strength of Mg–6Al–1Sn–0.3Mn (ATM610) reaches up to 96.8% of that of base material. Moreover, fracture occurs in the fusion zone of ATM610 instead of in the heat-affected zone of AM60 welded joint. The improvement in the properties is mainly attributed to the formation of Mg 2 Sn, which effectively obstructs the grain coarsening in the heat-affected zone, resulting in a relatively fine microstructure. The addition of 1% Sn improves the mechanical properties of AM60 welded joint.

Effect of Cu/Zn on microstructure and mechanical properties of extruded Mg–Sn alloys

In this paper, the effect of Cu and Zn addition on mechanical properties of indirectly extruded Mg–2Sn alloy was investigated. Mg–2Sn–0.5Cu alloy exhibits a moderate yield strength (YS) of 225 MPa and an ultimate strength of 260 MPa, which are much higher than those of the binary Mg–2Sn alloy, and the elongation (EL) evolves as ∼15.5%. Mechanical properties of the Mg–2Sn–0.5Cu alloy are deteriorated with more 3 wt-% Zn addition, and YS and EL are reduced as 160 MPa and ∼10%. The detailed mechanism is discussed according to the work-hardening rate and strengthening effect related to the grain sizes, second phases and macro-textures. Grain refinement and proper texture are believed to play a critical role in both strength and ductility optimisation.