Selective laser melting additive manufacturing of TiC/Inconel 718 bulk-form nanocomposites: Densification, microstructur
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dong Gua) College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 210016 Nanjing, People’s Republic of China; and Institute of Additive Manufacturing (3D Printing), Nanjing University of Aeronautics and Astronautics, 210016 Nanjing, People’s Republic of China (Received 2 April 2014; accepted 2 June 2014)
Selective laser melting (SLM) process was used to prepare the nanocrystalline titanium carbide (TiC)-reinforced Inconel 718 matrix bulk-form nanocomposites in the present study. An in-depth relationship between SLM process, microstructures, properties, and metallurgical mechanisms was established. The insufficient laser energy density (g) input limited the densification response of shaped parts due to the formation of either larger-sized pore chains or interlayer micropores. The densification of SLM-processed part increased to a near-full level as the applied g was properly settled. The TiC reinforcements generally experienced successive changes from severely agglomerated in a polygon shape to the uniformly distributed with smoothened and refined structures on increasing the applied g, while the columnar dendrite matrix exhibited strong epitaxial growth characteristic concurrently. The optimally prepared fully dense part achieved a high microhardness with a mean value of 419 HV0.2, a considerably low friction coefficient of 0.29, and attendant reduced wear rate of 2.69 104 mm3/N m in dry sliding wear tests. The improved densification response, SLM-inherent nonequilibrium metallurgical mechanisms with resultant uniformly dispersed reinforcement microstructures, and elevated microhardness were believed to be responsible for the enhancement of wear performance. I. INTRODUCTION
Nickel-based superalloys are typically used as hightemperature service parts in industrial and aerospace fields where good combination of high workability and mechanical properties are required.1 Inconel 718, a Ni–Cr–Fe-based austenitic superalloy, has found wide applications including in gas turbine wheel blades, nuclear reactors, containers, and fossil fuel components, due to its outstanding creep performance, tensile properties, oxidation resistance, and hot corrosion resistance.2 As the most attractive candidate material of hot-end components, Inconel 718 can retain its mechanical strength over a wide range of temperatures. This high-temperature strength was confirmed to be attributable to the inherent solid-solution strengthening and/or precipitation strengthening mechanisms.3 Though the Inconel 718 alloy was originally developed for the manufacture of gas turbine wheel blades four decades ago, it has found extensive applications in various fields afterward and still a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2014.130 1960
J. Mater. Res., Vol. 29, No. 17, Sep 14, 2014
http://journals.cambridge.org
Downloaded: 05 Mar 2015
been regarded as today’s most widely used superalloy in the world.4 Particularly, the environments that Inconel 718 superalloy has b
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