Research Article Influence of Milling Media on the Mechanical Alloyed W-0.5 wt.% Ti Powder Alloy Hadi Jahangiri, 1 Sultan Sönmez, 1,2 and M. Lütfi ÖveçoLlu 1 1 Particulate Materials Laboratories (PML), Department of Metallurgical and Materials Engineering, Faculty of Chemical-Metallurgical Engineering, Istanbul Technical University, Ayaza˘ ga Campus, 34469 Istanbul, Turkey 2 Department of Mechanical Engineering, Faculty of Engineering, Hakkari University, 30000 Hakkari, Turkey Correspondence should be addressed to Sultan S¨ onmez; sultansonmez@itu.edu.tr Received 3 April 2016; Accepted 14 July 2016 Academic Editor: Debdulal Das Copyright © 2016 Hadi Jahangiri et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te efects of milling atmosphere and mechanical alloying (MA) duration on the efective lattice parameter, crystallite size, lattice strain, and amorphization rate of the W-0.5 wt.% Ti powders were investigated. W-0.5 wt.% Ti powders were mechanically alloyed (MA’d) for 10 h and 20 h in a high energy ball mill. Moreover, morphology of the powders for various MA was analyzed using SEM microscopy. Teir powder density was also measured by helium pycnometer. Te dry milled agglomerated powders have spherical particle, while wet milled powders have layered morphology. Milling media and increasing of milling time signifcantly reduce the crystallite size. Te smallest crystallite size is 4.93 nm which belonged to the dry milled powders measured by Lorentzian method afer 20 hours’ MA. However, afer 20 hours, MA’d powders show the biggest crystallite size, as big as 57.07 nm, measured with the same method in ethanol. 1. Introduction Tungsten (W) alloys are attractive candidate materials for various high temperature structural applications due to their excellent properties such as high melting point, high modu- lus, high resistance of thermal shock, and low coefcient of thermal expansions (CTE) [1, 2]. However, alloying of mon- olithic W is mandatory for applications which require high strengths at elevated temperatures since mechanical proper- ties of monolithic W decrease signifcantly with increasing temperatures [3–11]. Small amounts of nickel (Ni) added as a transition element during mechanical milling (MM) and/or mechanical alloying (MA) activate sintering and enable the fabrication of fully dense W-based alloys and composites at lower temperatures than the usual sintering temperatures of W [7–13]. Similar to Ni, titanium (Ti) is probably a good candidate in triggering activated-sintering mechanism in W; however, its role as an activator in W has not been investigated yet. MM and MA are complex processes which involve the optimization of a number of variables to achieve a desired phase or microstructure. Milling media, milling time, ball to powder ratio, milling speed, and starting powder size range infuence both the stages of milling and the quality of milled product [14–16]. MA and MM in diferent milling media result in changing of powder properties and consequently alter mechanical, physical, and thermal properties of the fnal products. During the MA/MM process, the fattened layers overlap and form cold welds for sof powders which results in the formation of layered composite powder particles consisting of various combinations of the starting ingredients. On the other hand, the work-hardened elements or composite powder particles might be fractured at the same time. Tese competing events of cold welding (with plastic deformation and agglomer- ation) and fracturing (size reduction) continue repeatedly throughout the milling period [17–19]. Finally, a refned and homogenized microstructure will be obtained while the composition of the powder particles is of the same proportion of the starting constituent powders [20, 21]. Occasionally, metal powders are milled in a liquid medium also named as wet milling. However, if there is no liquid used during the milling process it is called dry milling [22, 23]. During wet milling, due to the low efciency such as retarding crystallite Hindawi Publishing Corporation Indian Journal of Materials Science Volume 2016, Article ID 7981864, 6 pages http://dx.doi.org/10.1155/2016/7981864