高速回転撹拌凝固によるCu-Al-Fe合金のミクロ組織の均質化と機械的性質の改善

Abstract

An investigation is made on the homogenization of microstructure and improvement of mechanical properties in Cu-Al-Fe alloy containing 9, 9.5 or 10 mass% aluminum and 3 or 4 mass% iron produced by the vacuum rheocasting in which the solidifying alloy is vigorously agitated at high rotation speeds from 60 to 70 rev/s of a stirrer immersed in the alloy.The torque value in Cu-10%Al-3%Fe alloy solidifying with rotation of stirrer at a speed of 70 s−1 is higher than that at a speed of 60 s−1 under the same cooling condition of 0.06 K/s. Homogeneous microstructures are formed by fragmentation of bamboo-leaf-like crystals with the rotation of stirrer at high speeds during the solidification of the Cu-Al-Fe alloys in the present study. The elongation value in Cu-9.5%Al-3%Fe alloy rheocast at a rotation speed of 60 s−1 is 141% for a strain rate of 0.93×10−4 at 1073 K. The elongation value in Cu-9.5%Al-4%Fe alloy rheocast at 60 s−1 is 172% for a strain rate of 0.93×10−4 s−1 at 1073 K. The elongation value in Cu-10%Al-3%Fe alloy rheocast at 60 s−1 is 147% for a strain rate of 1.85×10−4 s−1 at 1023 K. The elongation value in Cu-10%Al-4%Fe alloy rheocast at 60 s−1 is 294% for a strain rate of 0.93×10−4 s−1 at 1023 K. It is found that the elongation values in the present Cu-Al-Fe alloys rheocast at 60 s−1 are much larger than those in the conventionally cast alloys at elevated temperatures.