| Co-Investigator(Kenkyū-buntansha) |
青木 忠昭 東洋アルミニウム, 開発部, 主任
TAKESHIMA Masahiro College of Industrial Technology, Nihon University, 生産工学部, 助手 (00154998)
SUGAMATA Makoto College of Industrial Technology, Nihon University, 生産工学部, 助教授 (90059600)
AOKI Tadaaki Development Division, Toyo Aluminum Company, Ltd.
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1988: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1987: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
P/M materials of Al-Ti and Al-Ti-B alloys, which were processed from mechanically alloyed powders by cold pressing and hot extrusion, were used as grain refiner for aluminum castings. In Al-Ti-B alloys, constituent phase of Ti was varied as metallic Ti, TiAl_3 and TiB_2, and that of B as metallic B, TiB_2 and AlB_2, in order to discuss the mechanisms of grain refining in aluminum castings by the addition of Ti and B. Grain refiner was added to 99.9% aluminum melt,and cast into both metal mold and thermally insulated mold. The macro structures of the ingots were examined and the extent of grain refinement was evaluated.
When mechanically alloyed powder was directly added as grain refiner, attained grain refining was not as much as in case of addition of P/M material of the same composition, due to oxidation loss occurred in the former. The P/M Al-TiAl_3 alloy is more effective as the grain refiner than conventional Al-Ti mother alloy, due to finer TiAl_3 dispersion in P/M material. The P/M Al-Ti-B materials containing TiB_2 are less effective, and thus, TiB_2 is not an effective nucleant for aluminum. P/M materials containing TiAl_3 and AlB_2 are most effective under the condition of short time and lower temperature holding of the melt after addition of grain refiner. However, those containing metallic Ti and B are as effective as conventional Al-Ti-B alloy hardners. P/M materials with fine dispersion of TiB_2 or TiC showed higher strength at high temperatures than commercial aluminum alloys. Both TiAl_3 and TiAl were found to become amorphous aer mechanical alloying, but they became crystalized after heating for hot extrusion.
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