The high strengthtoweight ratio of magnesium alloys is usually a prime reason for considering these materials in engineering designs. Regarding for mgal alloys, the grain refinement caused by the addition of sic particles. Pdf grain refinement of magnesium alloys by mgzr master. Grain refinement of aluminum casting alloys1 casting. Introduction to magnesium alloys asm international. Addition of cao into mgca and mgzn alloys led to even more grain refinement. Grain refinement and mechanism of carbon inoculation in mg. In the case of the ecaped sample 8p the grain size distribution was also bimodal with the grain. An overview is given of grain refinement in aluminum casting alloys.
Grain refinement of aluminum casting alloys pdf free. Grain refinement of magnesium casting alloys by boron addition. Scientists and engineers for decades searched to utilize magnesium, known of its low density, for lightweighting in many industrial sectors. Grain refinement of magnesium and az19e magnesium alloy by. Grain refinement of magnesium alloys by zirconium brunel. Development of extrusiontorsion simultaneous processing for grain refinement in magnesium alloys m 2furui1 and t aida 1 professor, tokyo universityof technology, hachiouji, japan 2 associate professor, university of toyama, toyama, japan email. The second factor applies to all alloys and is related to the role of constitutional supercooling which, on the one hand, promotes grain nucleation and, on the other hand, forms a nucleationfree zone preventing further nucleation within this zone, consequently limiting the grain refinement achievable, particularly in low solutecontaining alloys. The diameter of a round having equivalent area to a grain is taken as the size of this grain. The grain size of a casing alloy has an important effect on its mechanical properties11, thus grain refinement is an important proves for magnesium and its alloys. The main objectives of grain refinement is to achieve a fine, uniform and equiaxed grain structure which in turn will lead to a much improved, stable and predictable set of mechanical properties. The reason for this may be seen by careful examination of the structure in a casting. Zn system is a good candidate for developing high performance magnesium alloys.
Hari babu nadendla from the brunel centres for advanced solidification techniques found a patented niobiumbased master alloy that not only filled the missing gap in grain refiners for magnesium alloys but offered significant advantages over titanium in aluminumsilicon alloys. Development of extrusiontorsion simultaneous processing. Ultrasonic vibration has been applied to a variety of liquid phase processes such as grain refinement and degassing in aluminum alloys. Grain refinement of magnesium casting alloys by boron.
Highintensity ultrasonic grain refinement of magnesium. Grain refinement is also very important for magnesium alloys where it improves most mechanical properties, and for many alloys, also improves creep and corrosion resistance. Grain refinement in continuously cast magnesium alloy. In the present research, grain refinement of magnesium alloy az91e using the chemical grain refinement method was studied. The most popular magnesium alloys for large automotive castings are based on the magnesiumaluminium alloy system.
Grain refinement of magnesium alloy by multiaxial alternative forging and hydrogenation treatment, magnesium alloys design, processing and properties, frank czerwinski, intechopen, doi. On the other hand, the understanding of grain refinement in aluminum. Zirconium alloying and grain refinement of magnesium alloys. This study investigates the grain refining efficiency and fading of mgb2 micro and nanoparticle added pure mg and az91e.
The role of alloy chemistry and zr particle number density. Grain refinement of mgal type alloys can be affected by many factors, and this increases the complexity of the issue. The mechanism is attributed to the al 4 c 3 particles existing in these alloys. During the past decades, achieving grain refinement in mgal alloys has been. Native grain refinement of magnesium alloys sciencedirect. Native grain refinement of magnesium alloys request pdf. It is shown that native grain refinement occurs only in magnesium alloys containing aluminium.
Influence of grain refinement on anisotropy in mechanical 57 p aki s t a n t h e n ucl e u s the nucleus a quarterly scientific journal of pakistan atomic energy commission ncleam, issn 00295698 influence of grain refinement on anisotropy in mechanical properties in wrought magnesium alloy az80 m. Improving the mechanical properties of magnesium alloys is one of important research fields for us in order to enlarge their application scope in the automobile industry. Grain refinement of highpurity mgal alloy ingots and. Although grain refinement of magnesium alloys has attracted intensive research 2, 57 the search for new and effective grain refiners.
Grain refinement in aluminum casting alloys tends to reduce the amount of porosity and the size of the pores and to improve mechanical properties, especially fatigue strength. An interesting observation that has been made about the grain refinement of these alloys is the influence of the source magnesium impurity level. It was previously agreed that grain refinement of magnesium alloys by zr was noticeable at low levels of soluble zr 4, but the subsequently detailed examinations showed that both insoluble. The addition of a small amount of zirconium to the magnesium melt can readily be used to reduce the ascast grain size by nearly two orders of magnitude as well as producing a nearly equiaxed and thus more uniform microstructure 2,3. Grain size measurement method following astm standard e11296. In addition, they also have wide applications in the fields of electronic. Chemical grain refinement of magnesium alloys can be done by dividing the magnesium alloys into two groups. Segregation and grain refinement in cast titanium alloys. High purity mg al type alloys have a naturally fine grain size compared to commercial purity alloys with the same basic composition. Grinding and polishing procedures for pure magnesium and its alloys 80 a.
Grain refinements of magnesium alloys inoculated by. For the work presented in this thesis, two of the most common mgal alloys, az91e and am60b, were chosen to determine the effect. Scientists at brunel university london have perfected the first ever grain refiner master alloy for magnesiumaluminium alloys. Mechanism for grain refinement of magnesium alloys by. The methodology also describes changes in grain size upon zr grain refinement of mg and has been used to analyse the potential for the use of sic to grain refine mgal alloys. Grain refinement is important for improving the microstructure and mechanical properties of magnesium alloys. Pdf grain refining mechanisms in magnesium alloys an overview. Grain refinement of magnesium alloys total materia article. Ultrasonic grain refinement of magnesium and its alloys. Grain refinement of az91d magnesium alloy by mgco 3. Effective grain refinement through equal channel angular pressing ecap for magnesium mg alloys has been demonstrated by many researchers.
The increased use of magnesium alloys with improved mechanical properties is a prominent strategy towards increasing fuel efficiency of vehicles and decreasing emissions. Although with the capability to achieve superplasticity, the batch mode nature of this method and the required repetitive processing to attain ultrafine grained structure have prohibited it from being widely used in largescale industrial production. Introduction magnesium alloys have large potential in fabrication of structural components of automobiles due to their high specific strength1. Quite different refining practices are needed depending upon the presence or absence of zirconium. The invention relates to a grain refining agent for cast magnesium products, comprising particles formed of a matrix of a ductile material, in which are uniformly dispersed nucleation particles of at least one element or compound selected from the group consisting of zirconium, silicon carbide, titanium carbide and mixtures of carbon with silicon or titanium, the nucleation particles having an. Novel approaches to grain refinement of magnesium alloys. Submitted in partial fulfillment of the requirements. Ascast titanium alloys characterized by fine grain structures are readily produced by inoculation of the alloys prior to or during the casting thereof with small amounts of at least one composition selected from the group consisting of titanium0. Grain refinement of magnesium alloys request pdf researchgate.
The figure shown through sem photo micrograph reveals the extent of modification of eutectic silicon in uninoculated and inoculated a356 alloy. The intensity can be controlled through the amplitude. Grain refinement of magnesium alloys by mgzr master alloys. Grain refiner breakthrough for magnesium alloys light.
The alloys that are free of aluminum are generally very well refined by zr master alloys. Pdf grain refinement of magnesium alloys mark easton. It covers fundamental aspects of alloy strengthening, recrystallization, details of microstructure and a unique role of grain refinement. Summary the purpose of the present study is to investigate the grain refinement process by boron addition and examine the effects of casting conditions and alloying elements on. Grain refinement of az91 magnesium alloy induced by alvb. Manual grinding and polishing procedure for pure mg. Grain refinement of magnesium alloys is required for improving mechanical properties to expand their application fields. The effect of cao on the mechanical properties of mg alloys was then studied through preparing two groups of samples mgca and mgcao based alloys. The effect of grain refinement on the castability of. Az91d magnesium alloy, grain refinement, mgco 3, microstructure 1. These dynamic factors are expected to diminish solute buildup ahead of the growing fronts, thereby diminishing the dependence of grain size on solute. In this paper, the c2cl6 and graphite powder were used as the potential grain refiners for am60 and az91 alloys, respectively. High stiffnesstoweight, castability, machinability, and excellent damping are desirable properties of magnesium alloys that factor.
Grain refinement of aluminium and magnesium alloys has been a challenging topic for decades and this is partly due to the complex nature of the mechanisms occurring during solidification and the lack of a common experimental method allowing comparison of data from different research groups. High purity mgal type alloys have a naturally fine grain size compared to commercial purity alloys with the same basic composition. Effect of grain refinement on the mechanical properties of. This article provides information on measurement of grain size in alloys and describes the. On the other hand, the understanding of grain refinement in aluminum bearing alloys is poor and in many cases confusing. Factors that influence alloying zirconium to magnesium with a mg33. Mgal based alloys are the most common commercial magnesium alloys, but grainrefining treatment is generally required, except for diecasting. An investigation has been made of highintensity ultrasonication of pure magnesium, binary, and commercial magnesium alloys to determine the role of solute under such dynamic conditions. Wo2003095689a1 grain refining agent for cast magnesium.
Grain refinement of az91d magnesium alloy by mgco 3 figure 2. Carbon inoculation is an effective method of grain refinement process for magnesium alloys containing aluminum. Grain refinement of magnesium alloy az91e ubc library. The mechanisms involved and the benefits of refinement are described. Ultrasonic grain refinement of magnesium and its alloys 165 effective ugr and for fully developed cavitation to occur in molten light metals, the ultrasound intensity needs to be t 80100 w cm2 eskin, 1998. Grain refinement and enhancement of mechanical properties of hot. The best refinement was obtained when the ti added was more than 0.
785 389 752 1485 1315 69 615 298 813 888 1657 1449 1250 1215 658 312 943 214 1065 192 1102 1436 358 453 1179 1034 935 1376 1579 210 740 1002 1157 1541 1452 613 323 862 674 230 573 68 439 1097 1219 1482 886 1145 691 796 1142