Experimental investigation into the EDM process of $\gamma $-TiAl

Authors: MOHAMMAD REZA SHABGARD, HOSSEIN FARAGI, BEHNAM KHOSROZADEH, KEIVAN AMINI, MIRSADEGH SEYEDZAVVAR

Abstract: Among the advanced materials, the $\gamma $-TiAl intermetallic compounds, due to their unique properties, are being gradually employed instead of nickel base super alloys, titanium alloys, and other high temperature alloys in the aerospace and automotive industries. These properties include maintaining high strength and creep resistance at elevated temperatures. Considering the features of this material and the limitations of traditional machining procedures, in this paper the results of utilizing the EDM process for $\gamma $-TiAl and the effects of input parameters, including discharge current and discharge duration, on output characteristics, comprising material removal rate, tool wear ratio, surface texture, and compositions and phases of machined surfaces, are presented. The results show that the EDM process affects surface integrity of $\gamma $-TiAl and causes the formation of surface cracks even at the lowest level of discharged energy. The increase in the discharge energy results in the formation of longer cracks with wider mouths. Due to the ingress of carbon and oxygen on the surface of the specimen, initial compositions and phases of machined surfaces are changed and brittle phases such as Ti$_{3}$Al and TiC are formed on the machined surfaces.

Keywords: EDM, $\gamma $-TiAl, material removal rate, tool wear rate, Ra, X-ray diffraction method, EDS, scanning electron microscopy

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