This article provides an overview of high-pressure die casting (HPDC)-related research undertaken at the EPSRC Future LiME Hub between 2015–2022. The project aimed to identify the cause of variability in the tensile ductility of die-cast structures, and to develop novel processing techniques to address this issue. Variability in tensile ductility was related to the size of large pores and non-metallic inclusions. It was proposed that these non-metallic inclusions formed during the pyrolysis of commercial plunger lubricants in the shot sleeve, and that these large pores derived from dilatational strains introduced during semi-solid deformation. Processing parameters and die design were found to significantly influence the microstructure of die-cast products, and the subsequent variability in tensile ductility. To close, recent progress on the application of intensive melt shearing to HPDC is reviewed. Intensive melt shearing was found to induce significant grain refinement in both Al and Mg alloys due to the effective dispersion of native oxide particles, and the use of these particles as heterogeneous nucleation substrates. The presence of native oxide particles also enabled the use of novel heat treatment procedures that avoided conventional issues such as surface blistering and geometrical distortion.

The search for more efficient methods for degassing aluminum alloy melts has always been of great interest for the metal industry because the presence of hydrogen and oxides in the melts’ prior casting was detrimental to the integrity and properties of the final products. In this work, we present an overview of the progress and key findings from the research and development of an innovative High Shear Melt Conditioning (HSMC) degassing technology during the Liquid Metal Engineering (LiME) Research Hub project. Compared to conventional rotary degassing, this novel technique was capable of working at higher rotor speeds to efficiently break and disperse the naturally occurring oxide bifilms in the melt and to capture and disperse each supplied inert gas bubble into many tiny bubbles throughout the whole melt. This resulted in the elimination of the need to degas fluxes to remove the oxides in the melt, the reduction in the gas flow required to reach the same level of hydrogen removal rate, and the minimization of the regassing effect after processing. The increased process efficiency allowed for reduced melt processing costs and, at the same time, improved the melt quality, which resulted in fewer defects and improved mechanical properties.