Effect of ceramic particle size on densification behavior, microstructure formation, and performance of TiB 2 -reinforce
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Effect of ceramic particle size on densification behavior, microstructure formation, and performance of TiB2reinforced Al-based composites prepared by selective laser melting Lixia Xi1, Dongdong Gu1,a), Kaijie Lin1, Shuang Guo1, Yang Liu1, Yuxin Li1, Meng Guo1 1
College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China; and Jiangsu Provincial Engineering Laboratory for Laser Additive Manufacturing of High-Performance Metallic Components, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China a) Address all correspondence to this author. e-mail: [email protected] Received: 20 October 2019; accepted: 9 December 2019
Al-based composites with micrometer and submicro-TiB2 reinforcements (1 wt%) have been produced by selective laser melting (SLM) from mixed powder under different processing conditions. The results show that the densification level of SLM-processed composite with submicro-TiB2 particles (>99.0%) was 0.3–2.4% larger than that of micrometer TiB2-reinforced composite under the same processing conditions. The distribution of Si precipitates in the matrix experienced a transform from continuous cellular to directional line-like morphology with reinforcement size decreasing from micron to submicron. The reinforcement size added in the matrix also exhibited a critical influence on preferred orientation and grain size of matrix. The SLM-processed composites exhibited improved tensile strength and ductility with a decrease of reinforcement size. High tensile strength of ∼400 MPa and elongation of ∼3.6% were obtained for the fine TiB2-reinforced samples, increasing by 6 and 13% compared with that of micro-TiB2–added samples, respectively.
Introduction Selective laser melting (SLM), as one class of additive manufacturing (AM) technologies, possesses high flexibility of manufacturing complex products almost without geometric constraints and achieves parts with tailorable structures by successive melting/rapid solidification of a loose powder bed in layer-by-layer fashion based on a computer-aided design (CAD) model [1–3]. With rapid development of SLM technology, numerous research efforts on the material design and processing parameters have been made to realize metallic components with high performances and complex structures in different laboratories [4–9]. Incorporation of ceramic reinforcements would complicate the laser absorptivity, thermodynamic properties within a small molten pool, as well as resultant microstructure evolution of composite components during the SLM process [10, 11]. Therefore, factors in terms of matrix/ceramic interactions and bonding, wetting characteristics, and dispersion homogeneity of
ª Materials Research Society 2020
ceramic particulates in matrix should be carefully considered to determine the optimal processing conditions and to achieve favorable property during SLM of composites. Currently, aluminum matrix composites (AMCs) have been successfully produced via SLM processing routes of both in situ an
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