Synthesis of nanocrystalline titanium carbide alloy powders by mechanical solid state reaction
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INTRODUCTION
SINCE 1970, the term mechanical alloying (MA) has been used to refer to the production of homogeneous composite particles with intimately dispersed uniform internal structure,m So far, the MA process has been employed widely for preparing several dispersion-strengthened superalloys.t24~ The MA process using ball milling and/or rod milling[7I techniques is a typical energizing and quenching procedure. These techniques have been successfully used for preparing several amorphous alloy powders with wide amorphization range. I849] The application of this unique process leads to the formation of many advanced materials that are difficult or impossible to be prepared by the traditional methods, e.g., A1-Nb, t19] A1-Ta,tl31 Ta-Cu, tl4] and A1-Hf1291binary systems. In fact, MA is more than just a unique process for preparing such numerous amorphous alloys. It has been applied to the production of metal nitrides [3~ and metal hydridesp3,34] by the so-called reactive ball milling methodY l More recently, El-Eskandarany eta/. [36]have shown that stoichiometric/3-SIC alloy powders can be synthesized by ball milling an equiatomic mixture of elemental silicon and graphite powders at room temperature. Titanium carbide (TIC) is a refractory material with certain of the characteristic properties of metals (luster, metallic conductivity, etc.) and, in addition, extraordinary hardness and toughness, excellent resistance to wear and abrasion, and infusibility. The cubic form of TiC (fcc structure) is very stable, has a very high melting point (about 3373 K), and does not decompose or undergo phase transformations in any temperature range of interest.t373 In fact,
M. SHERIF EL-ESKANDARANY, formerly Lecturer of Materials Science, Mining and Petroleum Engineering Department, Faculty of Engineering, Al-Azhar University, Nasr City 11884, Cairo-Egypt, is Visiting Professor, Institute for Materials Research, Tokoku University, Sendai 980-77, Japan. Manuscript submitted March 13, 1995. 2374-~VOLUME27A, AUGUST1996
TiC has received much attention due to its powerful usage in industrial applications as a hard coating to protect the surface of cutting tools from wear and erosion, extending the tool life.[381 In the industrial scale of production, TiC has been traditionally prepared either by direct union of the elements, by heating the metal in the vapor of a suitable hydrocarbon, or by heating the titanium oxide (or other compound) with carbon. I39] A significant amount of attention has recently been focused on another technique of producing TiC using a method called self-propagating high-temperature synthesis (SHS). [4~ For a successful SHS process, the reaction between Ti and C must take place at a temperature higher than the melting point of pure Ti (1943 K) because no reaction can occur below this temperatureJ41] Whereas all the TiC alloys are prepared by the previously mentioned techniques, the present study proposes a new process, the mechanical solid state reaction, for preparing TiC alloy powders. This process is based
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