アルミナイド金属間化合物の放電加工特性

抄録

Electro-discharge machining (EDM) of some structural intermetallic compounds was carried out by using a die-sinking type EDM machine. Three kinds of cast aluminides, TiAl, Ni₃Al and FeAl, were used as workpieces. Their machining properties such as removal rate, wear ratio of tool electrode and roughness of EDMed surface were evaluated. The EDMed surfaces and surfaces of tool electrodes after EDM were analyzed with X-ray diffraction patterns. The remaining strength of EDMed TiAl test pieces was also evaluated by 4 point bending test.
On all of the EDMed surfaces, cracks caused by shrinkage of the resolidified layers during cooling after discharges were observed. Using copper tool electrodes, each aluminide could be EDMed with small tool wear ratio. It was difficult to machine TiAl workpieces with large removal rate.
The degree of strength degradation of TiAl test pieces after EDM, was clearly influenced with the lamellate microstructure of the material and the EDM directions.