GRD Journals- Global Research and Development Journal for Engineering | Volume 5 | Issue 12 | November 2020 ISSN- 2455-5703
Relationship between the Diffraction Peak Intensity and Composition in (Ti1-xWx)C Powders Mohsen Mhadhbi Assistant Professor Department of Chemical Engineering Laboratory of Useful Materials, National Institute of Research and Physical-chemical Analysis
Abstract In this work, nanostructured (Ti1-xWx)C (0 ≤ x ≤ 0.2) powders were synthesized through solid state mechanical alloying (MA) process in a high-energy planetary ball mill (Fritsch Pulverisette 7) using Ti, W, and C powders mixture. Thus, MA was performed at room temperature under argon atmosphere to avoid oxidation. The relationship between the changes in diffraction peaks intensity and the composition of obtained powders was determined by using the structure factor calculations. However, the obtained results were compared with the theoretical ones. Keywords- X-Ray Diffraction, Carbide, Diffraction Peak, Composition, Nanostructure, Mechanical Alloying
I. INTRODUCTION Titanium carbides (TiC) are a materials of great industrial importance due to its excellent properties such as good wear resistance, high hardness, high thermal conductivity, etc. However, they possess some limitations like transverse rupture strength and low density [1]. These special characteristics allow for various applications like high temperature structural materials, in electrical discharge machining, and as abrasive for cutting tools and grinding wheels [2, 3]. Recently, several studies have focused on the investigations of nanostructured titanium carbide synthesized through mechanical alloying technique [4-10]. Mechanical alloying (MA) is a simple powder processing method that is employed to fabricate alloy powders, both in equilibrium and non-equilibrium, in the solid state. In fact, MA technique makes it possible to produce and control a refined, homogenous, and nanostructured microstructures [11, 12]. Furthermore, MA of elemental powder mixtures, with desired compositions, corresponding to the stoichiometry of intermetallic phases, which lead to the formation of powders with partially ordered or disordered solid solutions [13, 14]. Hence, MA is a significant process that contains cycle of cold welding followed by fracturing and re-welding, which cause an excellent inter-diffusion between powders particle [15, 16]. In this paper, a nanocrystalline (Ti,W)C powder was produced by MA. The morphology and microstructure of the refractory MA powder were studied. Hence, the relationship between the diffraction peak intensities and the composition of (Ti 1xWx)C solid solution was also studied based on structure factor calculations from the data of X-ray diffraction.
II. EXPERIMENTAL WORK A mixture of elemental powder Ti (< 40 μm, 99.9 %), C (5 μm, 99.9 %), and W (< 5 μm, 99.9 %) was sealed into a stainless steel vial (45 mL in volume) with 5 stainless steel balls (15 mm in diameter and 14 g in mass) in a glove box filled with purified argon to prevent oxidation. The ball to powder weight ratio was 70:1. The mechanical alloying (MA) procedure of 20 h was performed at room temperature using a high-energy planetary ball mill (Fritsch Pulverisette 7). The formed powders were characterized by X-ray diffraction using a Panalytical XPERT PRO MPD diffractometer with Cu Kα radiation. The High Score Plus program was used in order to analyze the XRD patterns and to obtain the position, the full-width at half maximum and the intensity of various peaks. The existing phases were determined based on the ICDD PDF2 data base. The XRD patterns were analyzed by the Fullprof program [17] using the Rietveld method [18]. The intensity of the diffraction peaks was measured from the measured raw data by integrating the area under the diffraction peak. The analytical functions relating the (111) and (200) diffraction peak intensities to the solid solution composition were deduced from the structure factor calculations. Assuming that the intensity of the diffraction peak can be determined only from the structure factor we can have a small variation that depends on other factors. In this context, we determined the powders diffraction patterns by computer calculations taking into account other parameters, such as instrumental broadening, strain factor.
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