Nano-sized TiN-reinforced composites: Fabrication, microstructure, and mechanical properties
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Nano-sized TiN-reinforced composites: Fabrication, microstructure, and mechanical properties Chunxin Li1, Xuewei Lv2,a), Xiaolong Wu1, Jie Chen1, Xuyang Liu3, Lijuan Pang4 1
Master Student of School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China Professor of School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China 3 Ph.D. Student of School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China 4 Ph.D. Student of School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China; and Faculty of Panzhihua University, College of Vanadium and Titanium, Sichuan 617000, China a) Address all correspondence to this author. e-mail: [email protected] 2
Received: 12 February 2019; accepted: 22 May 2019
Nano-sized TiN-reinforced Ti metal matrix composites were fabricated by powder metallurgical route, which includes high-energy ball milling pretreatment and subsequent hot-press sintering treatment. The phase composition and microstructure of the sintered samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results showed that N2 was absorbed and solubilized into TiH2 by milling pretreatment, and TiN was formed during sintering process and was fine to a grain size of 20–100 nm. The final phase composition of the composites was aTi, bTi, and TiN with solution N in matrix. Mechanical tests showed that with increasing milling time, the hardness of the composites increased by 31, 58, 93, and 101% compared with pure Ti. The compressive strength initially increased and later decreased to 2440 and 2120 MPa when milled for 1.5 and 2 h, respectively.
Introduction Ceramic-reinforced titanium matrix composites are widely used for high-temperature applications, such as functional aircraft and aerospace components, due to their enhanced elevated temperature strength, good creep performance, fatigue resistance, and wear resistance [1, 2, 3]. The influence of particle size of reinforcement on the strength, ductility, and failure mode of Metal matrix composites (MMCs) is well known [4]. The large ceramic particles tend to crack during mechanical loading, resulting in premature failure and low ductility of the composites. Therefore, decreasing the ceramic particle size can lead to a substantial improvement in the mechanical properties of the MMCs [5]. In recent years, considerable studies have been focused on the use of nanoparticles to reinforce metallic materials. Zhou et al. [6] studied 2.0 wt% nano-sized TiN/Al– Cu composite by casting and found that its yield strength, ultimate strength, and elongation are higher by 20.5, 22.5, and 104.5% than those of Al–Cu matrix alloy. Wang et al. [7] prepared TiB2/TiN nanocomposites by the spark plasma sintering technique with an average grain size of 1 lm and 300 nm of TiB2 and TiN, respectively. The composite exhibited very clean
ª Materials Research Society 2019
grain boundaries, and no amorphous phase or oxide l
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