銅―すず合金の初晶晶出に伴う湯流れ停止

抄録

  Using Cu-(0∼20wt%) Sn binary alloys the following were performed : fluidity tests with the volute shell mold method, viscosity measurements with the torsional oscillation method, thermal analysis and observation of the manner of flow. Cu-Sn alloys show minimum fluidity at about 2wt%Sn and high fluidity in dilute or high alloyed melts. It was revealed that flowing alloys stop their flow at fraction solid of 0.2∼0.4. Under the same conditions, the higher Sn-concentration is, the longer the alloy flows in complete liquid state and the shorter it flows in liquid-solid coexisting state. This results from the longer time it takes to cool down from the pouring temperature to liquidus, the shorter time from start of crystallization to stoppage of flow and the high viscosity in liquid-solid coexisting state. Fluidity of alloy is represented by the sum of the above two lengths.