Morphology Of Mg2Si Particles Research Articles

Modification of Mg2Si Phase Morphology in Mg-4Si Alloy by Sb and Nd Additions

We reported the effects of compound modification with Nd and Sb on the microstructure evolution and mechanical properties of Mg-4Si alloys. The characterization results showed that adding 1.0 wt.% Sb and 1.0 wt.% Nd to the alloy can effectively change the morphology of Mg2Si particles. The primary Mg2Si particles changed from coarse dendrites to regular polygons, and the average particle size decreased from 78.3 to 6.5 μm. Meanwhile, the Chinese eutectic Mg2Si became small short fiber. The experimental results showed that the Nd4Sb3 phase could be formed after adding 1.0 wt.% Sb and 1.0 wt.% Nd to the alloy. The Nd4Sb3 phase could act as the heterogeneous nucleation core of Mg2Si phase, which increased the nucleation rate of Mg2Si and improved the morphology of Mg2Si particles. The mechanical properties test found that the tensile properties and Brinell hardness of the alloy were improved with Sb and Nd alloyed. After adding 1.0 wt.% Sb and 1.0 wt.% Nd to the alloy, the ultimate tensile strength increased from 113 to 184 MPa, the elongation increased from 2.23 to 4.61%, and the Brinell hardness increased from 65.45 to 87.32 HB.

Effect of P addition on morphology of Mg2Si particles in magnesium alloy

Effect of P addition on morphology of Mg2Si particles in magnesium alloy

A Comparative Characterization of the Microstructures and Tensile Properties of As-Cast and Thixoforged in situ AM60B-10 vol% Mg2Sip Composite and Thixoforged AM60B

The microstructure and tensile properties of the thixoforged in situ Mg2Sip/AM60B composite were characterized in comparison with the as-cast composite and thixoforged AM60B. The results indicate that the morphology of α-Mg phases, the distribution and amount of β phases and the distribution and morphology of Mg2Si particles in thixoforged composite are completely different from those in as-cast composite. The Mg2Si particles block heat transfer and prevent the α-Mg particles from rotation or migration during reheating. Both the thixoforged composite and thixoforged AM60B alloy exhibit virtually no porosity in the microstructure. The thixoforged composite has the highest comprehensive tensile properties (ultimate tensile strength (UTS)) of 209 MPa and an elongation of 10.2%. The strengthening mechanism of the Mg2Si particle is the additive or synergetic effect of combining the load transfer mechanism, the Orowan looping mechanism and the dislocation strengthening mechanism. Among them, the load transfer mechanism is the main mechanism, and the latter two are minor. The particle splitting and interfacial debonding are the main damage patterns of the composite.

Effects of Sb addition on the modification of Mg 2Si particles and high-temperature mechanical properties of cast Mg–4Zn–2Si alloy

The effect of 2 wt.% Si and 0.2 wt.% Sb on the microstructure and high temperature mechanical properties of a cast Mg–4Zn alloy was investigated. Impression creep, hot hardness, and shear punch tests were used to evaluate the mechanical properties of the alloys at 200 °C. Addition of Si and Sb resulted in the formation of the thermally stable Mg 2Si and Mg 3Sb 2 intermetallic compounds, respectively. By the addition of Sb, the morphology of Mg 2Si particles changed from Chinese script to a more rounded edge type, being capable of providing better plasticity during shear deformation. The presence of thermally stable intermetallic particles and the modified morphology of Mg 2Si particles significantly improved the high temperature mechanical properties of the material.

Microstructure and mechanical properties of in situ Mg 2Si/AZ91D composites through incorporating fly ash cenospheres

5 wt.% of fly ash cenospheres with average size of 100 μm were added to the molten AZ91D magnesium alloy to prepare in situ Mg 2Si/AZ91D composites by means of compo-casting. The effect of the isothermal temperature and time of the composite slurry (the melt containing fly ash cenospheres) on the microstructure and mechanical properties of the composites was investigated. The effect of the solution treatment at 420 °C on the morphology of Mg 2Si particles in the composites was discussed. The results showed that compared with the matrix alloy, the tensile strength of the composites was higher at both room temperature and 150 °C. After the solution treatment, the shape of Mg 2Si particle transformed from the Chinese script Mg 2Si to spherical, and the tensile strength of the composites was further improved.

EFFECTS OF Sr ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Mg–9Al–1Si–0.3Zn ALLOY

Mg-Al-Si alloys (AS series alloys) with a high content of silicon performed low ductility and strengths because of large amount of coarse Chinese scripts Mg2Si particles distributed in the matrix. Trace elements, such as Ca, P, Sr and RE were selected to modify the morphology of Mg2Si particles. Among these, Sr showed remarkable modification effect, however, the modification mechanism was not clarified yet. In this work, the effects of Sr on the morphology of Mg2Si in Mg-9Al-1Si-0.3Zn (mass fraction, %) alloy and the mechanical properties were investigated, and the modification mechanism was explained by comparing Mg2Si morphologies. The Mg-9Al-1Si-0.3Zn alloy was composed of primary hopper Mg2Si particles of 40 µm in size, coarse Chinese scripts Mg2Si of 50—80 µm, island-like Mg17Al12 and the �-Mg matrix. 3D hopper crystals and Chinese scripts Mg2Si particles were extracted by the electrochemical method. Both morphologies reveal the corner effect which leads to the preferential growth orientation of edges and corners of the octahedron Mg2Si particle, respectively. When Sr was added into the alloy, the growth rates of both edges and corners of the Mg2Si particles were depressed significantly due to the adsorption of Sr on the surface of Mg2Si particles. When Sr addition went up to 0.32%, Mg2Si phase was fully modified to small polygonal particles of 5—20 µm. Moreover, the grain size of the alloy decreased from 210 µm to 160 µm with Sr increasing, which is in accord with the GRF (growth restriction factor) mechanism. The increasing of mechanical properties is mainly attributed to the refinement of Mg2Si phase.

Effect of Sr and Sb on Microstructure and Mechanical Properties of Mg-5AI-2Si Alloys

A study has been made on the effects of antimony (Sb) and strontium (Sr) additions on the microstructure of Mg-Al-Si alloys. Results showed that the additions of Sb and Sr can modify the morphology of Mg2Si particles from Chinese script shape to refined polygonal shape. Tensile strength and creep resistance were improved and tensile elongation was also increased in the modified alloy with Sb and Sr. The addition of Sr was more effective than Sb modification of AS52 alloy for refining microstructure and thus improving properties.

Behavior of Mg–6Al–xSi alloys during solution heat treatment at 420°C

The effect of solution heat treatment at 420°C on the morphology of Mg 2Si particles in Mg–Al–Si alloys was investigated. The Mg 2Si particles tended to be spherodized during the treatment due to the diffusion of Si atoms along the Mg 2Si/Mg interface, which is benefit the mechanical properties of the alloys.