Gradient Nanostructured Tantalum by Thermal-Mechanical Ultrasonic Impact Energy

Abstract

Microstructural evolution and wear performance of Tantalum (Ta) treated by ultrasonic nanocrystalline surface modification (UNSM) at 25 and 1000 °C were reported. The UNSM treatment modified a surface along with subsurface layer with a thickness in the range of 20 to 150 µm, which depends on the UNSM treatment temperature, via the surface severe plastic deformation (S2PD) method. The cross-sectional microstructure of the specimens was observed by electron backscattered diffraction (EBSD) in order to confirm the microstructural alteration in terms of effective depth and refined grain size. The surface hardness measurement results, including depth profile, revealed that the hardness of the UNSM-treated specimens at both temperatures was increased in comparison with those of the untreated ones. The increase in UNSM treatment temperature led to a further increase in hardness. Moreover, both the UNSM-treated specimens with an increased hardness resulted in a higher resistance to wear in comparison with those of the untreated ones under dry conditions. The increase in hardness and induced compressive residual stress that depend on the formation of severe plastically deformed layer with the refined nano-grains are responsible for the enhancement in wear resistance. The findings of this study may be implemented in response to various industries that are related to strength improvement and wear enhancement issues of Ta.

Surface Modification to Improve Properties of Materials

“…Furthermore, the fretting wear resistance was improved, so the technique may be useful for extending the lifespan of aircraft and nuclear components [12]. The technique was also used for the treatment of tantalum of a rather high purity [15]. The treatment caused both an increase in hardness and induced compressive residual stress.…”

“…The effect was particularly pronounced at high material temperature upon sonification. A plastically deformed layer with the refined nano-grains was observed and correlated to enhanced wear resistance [15].…”

Electrospun Polyvinyl Alcohol/d-Limonene Fibers Prepared by Ultrasonic Processing for Antibacterial Active Packaging Material

“…Ultrasonic processing methods have been applied in many homogeneous and heterogeneous reactions for agitating or homogenizing solutions. Ultrasound can generate strong thermal [ 22 ], mechanical [ 23 ], and super-mixing effects [ 24 ], as well as cavitation phenomenon [ 25 ]. Cavitation is the formation, growth, and implosive collapse of bubbles in a liquid [ 26 ], which can further homogenize the particles on a microscopic scale [ 27 ].…”

Increase in Strength and Fretting Resistance of Alloy 718 Using the Surface Modification Process

“…Lu has suggested that a gradient nanostructured material can improve both the strength and ductility compared to the nanostructured one [ 31 ]. Hence, it is suggested to generate a gradient nanocrystal structure using the UNSM process, which may lead to a further increase in both the strength and ductility [ 32 ]. Metallic materials are ductile, and they have a relatively lower strength but a relatively higher toughness or energy to failure because of greater ductility/post yield deformation.…”