Semi-solid processing of aluminum alloys requires a non-dendritic, equiaxed microstructure to obtain the necessary thixotropic flow behavior. The globular or spheroidal microstructure can be achieved by several different processes. Most commercial semi-solid alloys are produced by some sort of stirring mechanism during cooling of the billet, either mechanically or electromagnetically [1]. Another method that is used to achieve the necessary grain structure is the use of grain refiners. Using grain refiners to decrease grain size by increasing nucleation rate has been understood for several decades [2]. Recently, semi-solid thixoforging alloys were created by decreasing the pouring temperature of a wrought aluminum alloy melt during billet formation to just above the liquidus temperature. This process of forming semi-solid material is known as liquidus casting [3]. The mechanism for creating the non-dendritic, equiaxed structure is related to the Mullins-Sekerka instability criteria. The criteria states that an alloy with a very small undercooling coupled with a high saturation of nucleation sites would form an equiaxed structure [4]. This liquidus cast material has been thixoforged and has been found to have comparable properties to conventional semi-solid alloys [5]. In this letter we discuss the use of a near liquidus cast Al-Mg based alloy for semi-solid thixocasting. The difference between thixocasting and thixoforging is the required fluidity of the alloy, namely the ability of the alloy to flow in a narrow channel without solidifying [2]. A component of a fishing reel was both conventional high pressure die-cast from a liquid melt and thixocast from a liquidus cast billet using the same mold. Components were examined using both optical and electron microscopy and tensile samples were taken from the runner of the cast part, due to the geometry limitation of the fishing reel component (round shape with a wall thickness of about 2.5 mm). The alloy that was examined was the UK designated alloy LM5 with an average composition of Al-.10 wt % Cu-4.50 wt % Mg-.30 wt % Si-.60 wt % Fe-.50 wt % Mn-.10 wt % Ni-.10 wt % Zn.05 wt % Pb-.05 wt % Sn-.20 wt % Ti. The LM5 alloy was heated to 640 ◦C (10 ◦C above the liquidus temperature of this alloy) and then poured into cylindrical billet molds, 75 mm in diameter and 200 mm in height. Billets were cast in both water chilled and air cooled molds. Samples that were eventually thixocast were from the air cooled molds because this provided a more homogeneous cooling rate than that of the water chilled mold (the water chilled billets had severe problems with shrinkage cavities). Fig. 1 shows a micrograph of a billet cast in an air cooled mold. After cooling down, the samples were removed from the molds and subsequently induction heated into the semi-solid temperature range, between approximately 610 and 615 ◦C. During reheating, billets were ramped up at a rate of 6 degrees per second to the required temperature (610–615 ◦C) and then held for 3 min. Some samples were then water quenched for microstructural examination and other samples were thixocast. Fig. 2 shows a typical microstructure from a billet that has been induction heated and then water quenched. The grains at room temperature appear equiaxed, surrounded by the lower melting point eutectic phase with a grain size of about 100μm, a typical structure for thixocasting. Billets were thixocast using a Buhler H-400SC high pressure die casting machine. During casting, the semisolid material was injected into the cavity at gate speeds of 5–10 m/s and solidified under an intensification pressure of 90 MPa to investigate the thixocast-ability of the alloy. Fig. 3 is an example of a typical microstructure taken from a cross section of the cast part. It is noted that the grains still remain globular after thixocasting with a grain size of about 100μm. Previous work showed that a liquidus cast alloy was capable of being formed in a thixoforging operation [5], an operation that produces less complex shapes than thixocasting. The present