Semi-Solid Processing Of Alloys Research Articles

Progress of Semi-Solid Processing of Alloys and Composites in China

Following the rapid growth of the automotive and communication industries, components with high quality and low cost are eagerly desired in China. Various technologies have been developed in China to meet the demand, while semi-solid processing (SSP) of alloys and composites is one of the most successfully developed and practically applied technologies. The major SSP applied in China is the rheocasting in terms of the Swirled Enthalpy Equilibration Device (SEED) process. In this review, we start with a brief reviewing some common slurry preparation methods and recent innovations of the SEED process. Subsequently, we describe the general situation and some recent examples of successful development and applications of SSP in China. Lastly, the future directions in SSP of alloys and composites are highlighted in this frontier research field at the end of this review.

Current State of Semi-Solid Net-Shape Die Casting

Semi-solid processing of alloys is nearing the end of its fifth decade in existence. This promising manufacturing route has undergone a number of changes over the past five decades and apart from certain successful industrial applications, it appeared that it had become a niche technology with limited applications, notably in the automotive and consumer product markets. Nevertheless, despite the strong competition of traditional casting and in particular die-casting processes, and the emergence of Additive Manufacturing (AM), there seems to be a resurgence in demand for Net-Shape Die Casting of Semi-solid alloys as testified by the high numbers of delegates at the 15th SSM Conference at Shenzhen, China in September 2018. What follows is a brief review of the historical development of the process as well as more recent developments with an eye to future prospects.

Semi-Solid Processing of Alloys and Composites

A quick look through the past two centuries tells us that we may be in our third industrial revolution [...]

Semi-solid Processing of Alloys: Principles, Thermodynamic Selection Criteria, Applicability

Semi-solid processing (SSP) of alloys makes use of the thixotropic properties of two-phase mixtures of globulites and liquid. These materials whose viscosity decreases under shear deformation and increases again once the shear action ceases, can be handled almost like solids in the absence of shear stress and they can flow like viscous liquids when deformation forces are applied. SSP requires a wide melting interval of the alloy, a lowtemperature sensitivity of the phase fractions in the slurry and a tendency to form a fine-grained globulitic microstructure.The numeric simulation of solidification has proven useful for the selection of alloys to be processed in the semi-solid state. To obtain results applicable in practice, the methods to be used depend on the alloy systems, reaching from equilibrium calculations and Scheil-Gulliver estimations to diffusion simulations. All simulations depend on reliable thermodynamic and kinetic databases. Instead of using only the slope of the fraction liquid curve at 50% liquid as selection criterion, we suggest to use the thixo ranges ΔT40–60 for thixocasting and ΔT20–40 for thixoforging. Using these selection criteria we investigated the suitability of three Al alloys and three steels including the influence of compositional variations.So far, the industrial large-scale production of parts by SSP has been confined to aluminium alloys, although extensive development efforts are being made to apply the process to magnesium, to nickel alloys and to steels.

Semi-Solid Processing of Cast Iron

Semi-solid processing of alloys is becoming one of the key technologies for producing advanced materials. The present study aims to clarify mould filling characteristics and solidification structure in semi-solid processing of gray iron. The results indicate that the apparent viscosity and primary particle morphology have pronounced effects on the filling ability of semi-solid slurry. The particle segregation in the solidified sample is observed between the upper and lower part of the sample and is shown to decrease with the increase of stirring in semi-solid state. Finally semi-solid processed cast iron with the radial change of both the microstructure and mechanical property is obtained under the centrifugal effect acting on liquid/solid slurry.

The semi-solid processing of alloys and composites

The Second International Conference on Semi-Solid Processing of Alloys and Composites will be held on June 10–12, 1992, at MIT in Cambridge, Massachusetts.