Papers by Keyword: Wrought Alloy

Abstract: (Al3Ti)p/6351 composites were in situ synthesized via direct melt reaction between 6351 wrought aluminum alloy and K2TiF6 at 720°C. OM, SEM and EDS are utilized to analyze the microstructure and components of composites. The fusing agents of CaF2 and LiCl are mixed with K2TiF6 to lower the temperature of initial in situ reaction. The volume fraction of Al3Ti is 3%.The size of Al3Ti is in the range of 2~4μm, which is much lowered than that fabricated by conventional process. Due to the calcium element from CaF2 the size of Mg2Si phases are decreased to 1~2μm.The microns of independent silicon phases are also observed in the squeezed section. The grain size of α-Al is fined to 30~40μm, which is due to the disperse effect of Al3Ti. The tensile, yield properties and elongation are at room temperature are 365MPa, 320MPa and 10.2%.

Abstract: Tantalum (Ta) addition is one of the promising method for increasing the strength of Ni-based wrought alloys such as Inconel 718, because Ta is an element having a high melting temperature. For wrought alloys, it is necessary to make clear the phase relationships at 700~1000°C, but there is a few report on phase diagrams of Ni-Ta and Ni-Ta-Al systems at those temperatures. In this study, the phase diagram in Ni-rich region of Ni-Ta-Al system at 800°C, which is the important temperature for the practical use of the wrought alloys, was investigated. The equilibrium relations of each phase were examined by a conventional XRD, SEM/EDX and TEM observations. It was found that the γ-phase region expanded considerably towards Ta-rich compositional region in Ni-Ta-Al system at 800°C. Also, it was observed that the γ phase precipitated secondarily in the primary precipitated γ’ phase in Ni-10.5mol%Ta-5.5mol%Al alloy. Ni8Ta phase was not detected even in Ni-Ta binary system in this study, although this phase was reported previously.

Abstract: Mg-Al-Zn alloys containing 0.5% Ca were strip cast into sheets with a thickness of about 1.0mm by twin roll caster. It is found that the addition of Ca to Mg95Al5-XZnX (wt%)alloys prevents the oxidation and burning of molten, and makes the melting and casting easy. The as-cast Mg96Al4Zn0.5Ca0.5 alloy sheet has few cracks at the edge. With increasing Zn content, the generation of cracks occurs more markedly. The as-cast alloys have equiaxed grains with an average grain size of 10 μm. A fine microstructure is obtained. All the samples consist of single hcp-Mg phase. The yield and ultimate tensile strength of the as-cast sheets are in the range of 180 to 200 MPa and 265 to 275 MPa, respectively. The alloy Mg95Al2Zn2.5Ca0.5 shows an elongation of 21% as well as a high strength of 275 MPa. The annealing at 400 °C causes an improvement of elongation to 24% and 30% for Mg96Al4Zn0.5Ca0.5 and Mg95Al2Zn2.5Ca0.5,respectively. A further enhancement of mechanical properties is expected by an appropriate thermomechanical treatment. The as-cast Mg96Al4Zn0.5Ca0.5 sheet was deep drawn at 250°C and a drawing ratio of 2.0 without cracking . In summery, the Ca added Mg alloys are suitable for the production of Mg alloy sheets by strip casting and the cast alloy sheet have high strength with ductility and good formability

Abstract: A novel process named Controlled Diffusion Solidification (CDS) has been developed to circumvent problems that are typically associated with casting wrought aluminum alloy compositions into near net shaped components. The process involves bringing two precursor alloys of precisely controlled composition, temperature, and quantity into intimate contact, and then casting the resultant alloy using a conventional casting process to yield a component of predetermined composition with a microstructure that is similar to that of semi-solid processed alloys. Describing the many interactions that occur during solidification of aluminum alloys in a consistent manner is virtually impossible without the use of computational tools that are based on thermodynamic models. In this paper, we describe how the CALPHAD method, which allows calculating all the necessary data from thermodynamic model parameters, was used along with theoretical calculations and empirical rules to allow describing the Gibbs free energy of each phase in the alloy system and yield quantitative data that guided the development and optimization of the CDS method.

Abstract: The use of magnesium in motor vehicles today and in future depends on numerous technical and economical factors, though the cost factor is essential. How might use of magnesium in vehicles develop, what prerequisites are necessary, what R&D efforts are required These questions will be addressed as follows based on component and project examples. The main focus of the current magnesium applications can be seen in the drive train and in the interior. In the short term, these applications will be further expanded: doubling the amount is feasible. This will be supported by the currently developed Mg alloys with extended application potential (creep resistance). Mg components in the body, Mg-sheets and Mg-extrusions applications will appear initially in niche-market and premium vehicles. This can prepare the way for and eventually lead to greater use of Mg in volume-production models as part of a multi-material design concept. The essential prerequisites for such increased use of magnesium will be discussed.