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Wenchao Yang - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous nucleation in mg zr alloy under die Casting Condition
Materials Letters, 2015Co-Authors: Wenchao Yang, Lin Liu, Jun Zhang, Z FanAbstract:Abstract Heterogeneous nucleation behaviour was studied in die Casting Mg–Zr alloy. It was found that up to 48.78% Zr particles could be used as nuclei and the nucleation occurred on curved and faceted interfaces. It meant that the size effect of nuclei in Mg–Zr alloy was insignificant, and this nucleation behaviour was independent on any crystallography orientation. Therefore, a large range of Zr nuclei could be activated simultaneously under the large undercooling through the delayed recalescence resulting in a very high nucleation efficiency.
Z Fan - One of the best experts on this subject based on the ideXlab platform.
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heterogeneous nucleation in mg zr alloy under die Casting Condition
Materials Letters, 2015Co-Authors: Wenchao Yang, Lin Liu, Jun Zhang, Z FanAbstract:Abstract Heterogeneous nucleation behaviour was studied in die Casting Mg–Zr alloy. It was found that up to 48.78% Zr particles could be used as nuclei and the nucleation occurred on curved and faceted interfaces. It meant that the size effect of nuclei in Mg–Zr alloy was insignificant, and this nucleation behaviour was independent on any crystallography orientation. Therefore, a large range of Zr nuclei could be activated simultaneously under the large undercooling through the delayed recalescence resulting in a very high nucleation efficiency.
S E Stanzltschegg - One of the best experts on this subject based on the ideXlab platform.
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influence of porosity on the fatigue limit of die cast magnesium and aluminium alloys
International Journal of Fatigue, 2003Co-Authors: H Mayer, M Papakyriacou, B Zettl, S E StanzltscheggAbstract:Abstract High cycle fatigue properties of high-pressure die-cast magnesium alloys AZ91 hp, AM60 hp, AE42 hp, AS21 hp and of similarly produced cast aluminium alloy AlSi9Cu3 have been investigated. Ultrasonic fatigue tests up to 10 9 cycles show mean fatigue limits of approx. 38–50 MPa (magnesium alloys) and 75 MPa (AlSi9Cu3) in the tested Casting Condition. Fatigue cracks initiated at porosity in 98.5% of the samples. Considering porosity as initial cracks, specimens fail, if critical stress intensity amplitude, K cr is exceeded. K cr of the magnesium alloys range from 0.85±0.05 to 1.05±0.05 MPa√m, and 1.85±0.10 MPa√m was found for AlSi9Cu3. Below K cr , fatigue cracks may initiate at porosity, however, do not propagate until failure. Using K cr , the statistical distribution of defects is linked to the fracture probability at different stress amplitudes.
H Mayer - One of the best experts on this subject based on the ideXlab platform.
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influence of porosity on the fatigue limit of die cast magnesium and aluminium alloys
International Journal of Fatigue, 2003Co-Authors: H Mayer, M Papakyriacou, B Zettl, S E StanzltscheggAbstract:Abstract High cycle fatigue properties of high-pressure die-cast magnesium alloys AZ91 hp, AM60 hp, AE42 hp, AS21 hp and of similarly produced cast aluminium alloy AlSi9Cu3 have been investigated. Ultrasonic fatigue tests up to 10 9 cycles show mean fatigue limits of approx. 38–50 MPa (magnesium alloys) and 75 MPa (AlSi9Cu3) in the tested Casting Condition. Fatigue cracks initiated at porosity in 98.5% of the samples. Considering porosity as initial cracks, specimens fail, if critical stress intensity amplitude, K cr is exceeded. K cr of the magnesium alloys range from 0.85±0.05 to 1.05±0.05 MPa√m, and 1.85±0.10 MPa√m was found for AlSi9Cu3. Below K cr , fatigue cracks may initiate at porosity, however, do not propagate until failure. Using K cr , the statistical distribution of defects is linked to the fracture probability at different stress amplitudes.
Matthew S. Dargusch - One of the best experts on this subject based on the ideXlab platform.
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effect of ultrasonic treatment on the alloying and grain refinement efficiency of a mg zr master alloy added to magnesium at hypo and hyper peritectic compositions
Journal of Crystal Growth, 2019Co-Authors: B Nagasivamuni, Gui Wang, David H. Stjohn, Matthew S. DarguschAbstract:Magnesium – Zirconium master alloys are the dominant grain refiner for a range of commercial magnesium alloys that exhibit good elevated temperature properties. However, the grain refining efficiency achieved by the master alloy is relatively low because Zr particles quickly settle to form sludge. In this study ultrasonic treatment (UST) is applied to investigate whether the grain refinement efficiency can be improved by increasing the Zr solute content, producing a more uniform dispersion of Zr particles and minimizing sludge formation. It was determined that, for a range of Zr contents from 0.2 to 1.0 wt% Zr, UST of the melt above the liquidus temperature decreased the grain size due to an increase in the amount of solute Zr and the number of Zr particles. For Zr contents less than 0.5 wt% the grain size decreased further when UST was applied from above to below the liquidus temperature to include the onset of nucleation of α – Mg grains. Additionally, the application of UST substantially decreased the amount of sludge which increased the number density of Zr particles and improved their likelihood of successful nucleation. The Interdependence nucleation model was successfully applied to predict the grain size of each Casting Condition where the parameter z relates to the temperature gradient which in turn is affected by the acoustically-induced convection. A lower value of z when UST is applied facilitates nucleation and the survival of grains. The factors affecting grain refinement under each Condition are evaluated in terms of solute and particle Zr contents, cavitation and acoustic streaming and their effect on nucleation and as-cast grain size.