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• A new kind of 410 stainless steel-based MAPs was fabricated through gas nitriding. • The core–shell structured MAPs have good finishing performance. • The surface hardness and wear resistance of the MAPs were improved. The traditional Fe-based magnetic abrasive powders (MAPs) are prone to degrade by corrosion and oxidation. The extremely low stability to some extent limits the development of magnetic finishing. In this study, a new kind of 410 stainless steel-based spherical MAPs with core–shell structure was synthesized by gas nitriding. The nitride layer shows the dendrite structure containing (Fe, Cr) 4 N phase and lath-like CrN phase. The Zirconium tube roughness can be reduced from 0.280 to 0.153 μm. The origin of the good finishing performance was investigated through the Vickers hardness and nanoindentation tests. [ABSTRACT FROM AUTHOR]

Abstract: In order to improve the surface mechanical properties of GB-5083 aluminum alloy, titanium–aluminum–nitrogen thermo-reactive diffusion coatings were fabricated on the surface of Al substrate through deposition and nitriding process. The substrates were firstly deposited with pure Ti film by magnetron sputtering and then plasma nitrided in an atmosphere of 40% N2–60% H2 at 460°C. The as-obtained coatings under different nitriding time were characterized by using X-ray diffractometer (XRD), scanning electron microscopy (SEM), microhardness tester, scratch tester and pin-on-disc tribometer. Results showed that the multiphase coating comprising two sub-layers (i.e. the outside TiN0.3 layer, and the inside Al18Ti2Mg3 layer) can be obtained. The coating thickness increased slightly with increasing nitriding time. The hardness of the as-obtained coating has reached about 600HV, which is much higher than that of the GB-5083 Al substrate. The critical load of adhesive failure for the coating obtained by 16h nitriding reached 13N. Compared with the untreated Al alloy, the wear rate of the coated sample decreased 65% after 24h nitriding treatment. The analysis of worn surfaces indicated that the coated GB-5083 Al alloy exhibited predominant abrasive wear, whereas the uncoated one showed severe adhesive wear. [Copyright &y& Elsevier]

Highlights: [•] A novel duplex surface treatment on 2024 Al alloy was proposed. [•] A multiphase layer composed of TiN0.3, Al3Ti and Al18Ti2Mg3 was prepared on the surface of 2024 Al alloy. [•] The microstructures of TiN0.3, Al3Ti and Al18Ti2Mg3 were characterized by SEM and TEM. [•] The surface hardness of the multiphase layer reached to 590 HV0.01, five times harder than 2024 Al alloy. [•] The wear resistance of 2024 Al alloy was improved significantly. [ABSTRACT FROM AUTHOR]

Abstract The microstructure and mechanical properties of roll bonded and annealed SUS304/Q235 multilayer steels were investigated by using optical microscope (OM), scanning electron microscope (SEM), electron probe microanalysis (EPMA), electron backscattered diffraction (EBSD), Transmission electron microscope (TEM) and universal testing in detail. Hot rolling with high reduction ratio could strengthen the clad interface due to the interface oxides rupture, increased residual compression stress and sufficient alloy element diffusion. The hardness and tensile strength are increased, while the fracture elongation is decreased sharply with the increasing cold rolling reduction ratio. The hardened SUS304 layers are easy to strain softening, leading to localized necking, wave-like clad interface and nonuniform layer thickness during the cold rolling process. The annealed grain orientations in the separated SUS304 layers also reveal that the overall grain boundaries are across the Q235 layer, which is attributed to the grain coarsening across clad interface during the annealing process. At the grain boundaries in the SUS304 layer, the austenite-to-ferrite transition reveals the serious grain boundary diffusion behavior. Moreover, tensile fracture characteristics reveal that interface delamination cracks are inhibited by annealing treatment, which may be attributed to the sufficient alloy element diffusion at the clad interface. [ABSTRACT FROM AUTHOR]

This study aimed to investigate dislocation structures in CuNiCoFeCrAl 0.3 alloy particles using a transmission electron microscope (TEM). A non-equiatomic CoCrFeCuNiAl 0.3 high-entropy alloy composite (HEAC) reinforced with TiC5vol% nanoparticles was produced by mechanical alloying and spark plasma sintering. X-ray and TEM microanalyses confirmed the predominance of a nanotwinned single-phase face-centered cubic (FCC) solid solution with TiC nanoparticles. Further findings revealed that twin structure formation in FCC high-entropy alloys (HEAs) by the powder metallurgy technology was dependent on dislocations and the stratified structure formed in particles during mechanical alloying, low stacking-fault energy γ SF , pressure, and hardness phase. The TiC5vol%–CoCrFeCuNiAl 0.3 HEAC had the following excellent comprehensive mechanical properties: yield strength, 1582 MPa; fracture strength, 2185 MPa; and plastic strain, 23.60%. The dislocation glide and semi-twin expansion in HEAs provided excellent plasticity, while TiC particles and transgranular twins contributed to the material strength. [ABSTRACT FROM AUTHOR]