Synthesis of nanoscale spherical TiB 2 particles in Al matrix by regulating Sc contents
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Synthesis of nanoscale spherical TiB2 particles in Al matrix by regulating Sc contents Jing Sun1,a), Xuqin Wang2, Lijie Guo2, Xiaobo Zhang3, Haowei Wang3 1
Research and Development Department, Shanghai Aerospace Equipment Manufacturer Limited Company, Shanghai 200245, China; and State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China 2 Research and Development Department, Shanghai Aerospace Equipment Manufacturer Limited Company, Shanghai 200245, China 3 State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China a) Address all correspondence to this author. e-mail: [email protected] Received: 31 August 2018; accepted: 20 November 2018
In situ TiB2 particles with polyhedral or near-spherical morphology with more high-index crystal planes exposed were prepared by controlling the addition amount of Sc in commercial pure aluminum matrix. As the content of Sc increased, TiB2 morphology transformed from hexagonal platelets to polyhedral or near-spherical morphology with a decrease in particle size. In the present paper, a simple method to prepare near-spherical in situ TiB2 particles in Al matrix was explored and it was found that the reinforcement distribution was improved significantly. The different growth mechanism of TiB2 particles in Al and Al–Sc systems was discussed. The key reason for the morphology evolution was that the Sc was preferentially adsorbed on 1212 , 1120 , and 1011 which would inhibit the growth of these faces effectively and retain a lower-energy state of the polyhedral or quasispherical TiB2 particles in Al–Sc systems.
Introduction TiB2/Al composites are widely used in aerospace and automobile industries due to their high modulus, high strength, light weight, and excellent processability [1, 2]. However, the properties of the composites are significantly influenced by the morphology and distribution of the reinforced TiB2 particles, because of different stress states and interface bonding that exist around particles with different morphologies. The sharp corners in the particles may scratch the matrix in the service process and ultimately degrade the material performance dramatically. Therefore, it is necessary to understand the growth mechanism of TiB2 and the influence of different elements and then to realize the shape control during the formation of in situ TiB2 particles. Generally, TiB2 exhibits hexagonal prism in aluminum matrix and the diameter ranges from few tens of nanometers to a few micrometers [3, 4, 5, 6]. Due to their excellent properties, TiB2 attracts increasing attention as a reinforcement of composite materials [7]. The size and morphology of particles will significantly influence the mechanical property of the composites due to different stress states existing around the particles with different shapes [8, 9, 10]. Therefore, the shape control of
ª Materials Research Society 2019
the TiB2 particles in in situ process is very important. However, the morphology of TiB2 is rather diffi
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