| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1997: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
In the present research project, the effects of oxide species and microstructure of matrix phase on the strength properties of mechanically alloyed oxide dispersion strengthened ferritic steels were investigated and also the effects of oxide species and thermomechanical treatments just after the mechanically alloying procedure on the oxide particle dispersion behaviors and microstructure of matrix phase were clarified.
Investigattion were made on the 5 kinds of oxide species of Y_2O_3, ZrO_2, TiO_2, MgO and Al_2O_3 and the 2 kinds of thermomechanical treatments after the MA processing, such as higher temeprature treatment and lower temperature one.
It was clarified that the particle dispersion behavior was decided by the oxide specy and very tiny particles of Y_2O_3 distributed uniformly in the matrix. On the other hand, other particles of ZrO_2, TiO_2, MgO and Al_2O_3 did not necessarily distributed uniformly and in some places large particles (diameter : 200 to 300nm) existed. The thermomechanical treatments after the MA processing did not affect the particle dispersion behaviors, but had very large effects on the microstructure of matrix phase. The thermomechanical treatment at higher temperature introduced very small grains (including sub-grains) in the matrix. Uniform distribution of tiny partilces of Y_2O_3 and microstructure of very small grain size gave the largest strength.
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