Rapid synthesis of bulk Ti 2 AlC by self-propagating high temperature combustion synthesis with a pseudo-hot isostatic p
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Xiaodong Hea) Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080, China; and School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798
Yibin Li Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin 150080, China
Chuncheng Zhu Department of Chemistry, Harbin Normal University, Harbin 150000, China
Sam Zhangb) School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Received 14 January 2009; accepted 9 May 2009)
In this study, the dense polycrystalline Ti2AlC was synthesized by self-propagating high-temperature combustion synthesis with the pseudo–hot isostatic pressing process (SHS/PHIP). The resultant phase purity is highly dependent on the mol ratio of raw powders. The Ti2AlC was densified by applying pressure after the SHS reaction. The resultant sample mainly contains typical plate-like nonstoichiometric Ti2AlCx (x = 0.69) with grain size of 6 mm. The sample shows the Vickers hardness of 5.8 GPa, highest flexural strength of 432 MPa, compressive strength of 1037 MPa, and fracture toughness of 6.5 MPam1/2. No indentation cracks in Ti2AlCx were observed, indicative of a damage material nature. The reaction mechanism for the formation of SHS/PHIPderived Ti2AlC is also discussed based on differential thermal analysis and x-ray diffraction results. I. INTRODUCTION
Ti2AlC, as one of MAX ternary compounds (Mn+1AXn, where M = early transition metal, A = group IIIA or IVA element, X = C and/or N, n = 1–3), has attracted great attention recently because of its unique combination of both metal- and ceramic-like properties: low density (4.11 g/cm3),1 high Young’s modulus (277.6 GPa),2 good thermal and electrical conductivity (46 106 W/K and 2.78 106 S/m),1,3 easy machinability, and good oxidation resistance.4 At room temperature, Ti2AlC with preferentially oriented microstructures exhibits ductile behavior and unusually high irreversible energy absorption behavior during cyclic deformation, a)
Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/jmr_policy DOI: 10.1557/JMR.2009.0327 2528
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J. Mater. Res., Vol. 24, No. 8, Aug 2009 Downloaded: 11 Mar 2015
particularly in its porous state.5 These properties could render this ternary compound to be a suitable candidate for many high-temperature structural and functional applications. Although Ti2AlC was first synthesized and its structure was determined in the late 1960s,1,6 until now, only a few methods for the fabrication of bulk Ti2AlC have been reported. Barsoum et al.3,7 used hot pressing (HP) or reactive hot isostatic pressing (HIP) of Ti/Al4C3/C pellets to produce high-purity Ti2AlC samples. Wang and Zhou8 synthesized bulk Ti2AlC by solid–liquid reaction synthesis
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