Abstract: In carrying out of a thixocasting process, a material in a semi-molten state is produced by heating an aluminum alloy material which has a thermal characteristic that a first angled endothermic section generated by the melting of a eutectic crystal and a second angled endothermic section generated by the melting of a component having a melting point higher than an eutectic point exist in a differential calorimetric curve. A start point of a primary pressing stage is established at a point when the temperature T of the material is in a range of T.sub.1 <T.ltoreq.T.sub.4 in the relationship between the temperature T.sub.1 of a rise-start point in the first angled endothermic section and the temperature T.sub.4 of a peak of the second angled endothermic section. At the primary pressing stage, the charging of the material into the cavity in a casting mold is completed. A start point of a secondary pressing stage is established at a point when the temperature T of the material is in a range of T.sub.1 <T.

Abstract: In a thixocasting process, the following steps are used: a step of subjecting, to a heating treatment, an Al-Si based alloy material having a hypo eutectic crystal composition and a characteristic that a first angled endothermic section appearing due to the melting of a eutectic crystal and a second angled endothermic section appearing due to the melting of a component having a melting point higher than a eutectic point exist in a differential calorimetric curve, thereby preparing a semi-molten Al-Si based alloy material having solid and liquid phases coexisting therein; a step of pouring the semi-molten Al-Si based alloy material into a cavity in a casting mold under pressure; and a step of solidifying the semi-molten Al-Si based alloy material under pressure. When the temperature of a rise-start point in the first angled endothermic section is represented by T.sub.1, and the temperature of a drop-end point the first angled endothermic sections is represented by T.sub.

Abstract: In carrying out of a thixocasting process, a material in a semi-molten state is produced by heating an aluminum alloy material which has a thermal characteristic that a first angled endothermic section generated by the melting of a eutectic crystal and a second angled endothermic section generated by the melting of a component having a melting point higher than a eutectic point exist in a differential calorimetric curve. A start point of a primary pressing stage is established at a point when the temperature T of the material is in a range of T.sub.1 <T.ltoreq.T.sub.4 in the relationship between the temperature T.sub.1 of a rise-start point in the first angled endothermic section and the temperature T.sub.4 of a peak of the second angled endothermic section. At the primary pressing stage, the charging of the material into the cavity in a casting mold is completed. A start point of a secondary pressing stage is established at a point when the temperature T of the material is in a range of T.sub.1 <T.