Process for producing a thixocast semi-molten material

摘要

Solid and liquid phases coexist in a semi-molten casting material. A plurality of composite-solid phases having liquid and solid phase regions and a plurality of single-solid phases exist as the solid phases in a mixed state in an outer layer portion of the semi-molten casting material. If the sectional area of the solid phase region is represented by A, and the sectional area of the solid phase region is represented by B in one of the composite-solid phases, the liquid phase enclosure rate P of the composite-solid phase is defined as being represented by P={B/(A+B)}x100 (%). The liquid phase enclosure rate P of the single-solid phase is equal to 0 (%). When two groups are selected from a class of the solid phases, for example, by first and second straight lines so as to include a plurality of the solid phases, average values M1 and M2 of liquid phase enclosure rates of, for example, six solid phases in each of the first and second groups are represented by M1=(P1+P2 - - - +P5+P6)/6 and M2=(P7+P8 - - - +P11+P12)/6, and an average value MM of the average values M1 and M2 is set in a range of MM>/=20%. This inhibits the flow-out of the liquid phases from the outer layer portion in the thixocast semi-molten casting material.