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Transient liquid bonding (TLP) of IC10 single crystal with GH3039 alloy was carried out using BNi2 interlayer. Microstructure evolution and mechanical properties of the joints bonded at 1050-1200 °C for 2 h were investigated. The precipitates in the DZ on the GH3039 side gradually decreased and disappeared with the increase of the bonding temperature. The formation mechanism of the TLP joint was proposed and the asymmetry of the bonding was discussed. Tensile strength and microhardness tests were conducted to investigate the mechanical properties of the joints. The layer of borides with high hardness in the joint bonded at 1150 °C significantly reduced the room-temperature tensile strength but had little effect on the high-temperature tensile strength of the joint. The layer of borides became the preferential position to crack during both room-temperature and high-temperature tensile tests. The joints with dispersive precipitates had the highest room-temperature tensile strength and the homogenized joints showed the best ductility. [ABSTRACT FROM AUTHOR]

Transient liquid bonding (TLP) of IC10 single crystal with GH3039 alloy was carried out using BNi2 interlayer. Microstructure evolution and mechanical properties of the joints bonded at 1050–1200 °C for 2 h were investigated. The precipitates in the DZ on the GH3039 side gradually decreased and disappeared with the increase of the bonding temperature. The formation mechanism of the TLP joint was proposed and the asymmetry of the bonding was discussed. Tensile strength and microhardness tests were conducted to investigate the mechanical properties of the joints. The layer of borides with high hardness in the joint bonded at 1150 °C significantly reduced the room-temperature tensile strength but had little effect on the high-temperature tensile strength of the joint. The layer of borides became the preferential position to crack during both room-temperature and high-temperature tensile tests. The joints with dispersive precipitates had the highest room-temperature tensile strength and the homogenized joints showed the best ductility. [ABSTRACT FROM AUTHOR]

Due to the poor wettability of the AgCuTi alloy on the SiO2f/SiO2 composite, direct brazing of the composite with an Invar alloy could hardly achieve a reliable joint. To overcome that, the SiO2f/SiO2 composite was decorated with few-layer graphene (FLG) by a plasma enhanced chemical vapor deposition (PECVD) method. Sessile drop experiments indicate that the contact angle dropped from 123.8° to 50.7° after FLG was grown on the surface of the SiO2f/SiO2 composite. Afterwards, the effects of brazing temperature and Ti contents on the microstructure evolution and mechanical properties of joints (Invar/SiO2f-SiO2 modified with FLG) were investigated. The typical interface structure of the joint is SiO2f- SiO2/Ti5Si3 + TiO2 + CuxTi6 - xO(x = 2,3)/Ag(s,s) + Cu(s,s) + Cu-Ti blocks/wave-like Fe2Ti + Ni3Ti/Ag(s,s) + Cu(s,s) + Fe2Ti + Ni3Ti blocks/Invar. As the brazing temperature and Ti contents increase, the reaction layer on the SiO2f/SiO2 side becomes thicker and cracks gradually propagate. Meanwhile, a few dispersive Fe2Ti + Ni3Ti phases change into large-area wave-like compounds and more Cu-Ti compounds form with the increase of the Ti content. The microstructure evolution significantly affects the shear strength of the brazed joints. The highest shear strength is 26 MPa brazed at 860 °C for 10 min with 4.5 wt.% Ti content. [ABSTRACT FROM AUTHOR]

Highlights: [•] M50NiL steel is nitrocarburized with and without rare earth (RE) addition. [•] RE addition can increase the surface hardness and layer thickness. [•] RE can increase C, N contents and proportion of iron nitrides in treated layers. [•] Plasma nitrocarburizing can significantly improve the wear resistance of M50NiL steel. [•] RE addition could further improve the wear properties of the treated layers. [ABSTRACT FROM AUTHOR]

Pulsed plasma arc additive manufacturing (PPAM) is a novel additive manufacturing (AM) technology due to its big potential in efficiency, convenience and cost-savings comparing with other AM process. In this research, several Ti-6Al-4V thin walls were deposited by an optimized weld wire-feed PPAM process, in which the heat input was gradually decreased layer by layer. The deposited thin wall consisted of various morphologies with different microstructure, such as epitaxial growth of prior β-grains, martensite and horizontal layer bands of Widmanstätten, which depend on the heat input, multiple thermal cycles and gradual cooling rate in the deposition process. Reducing heat input of each bead and using pulsed current in the PPAM process, the microstructure of thin wall was refined. Meanwhile, the thin wall was strengthening and toughening. The average yield strength (YS) and ultimate tensile strength (UTS) reach 909 MPa and 988 MPa, respectively, and elongation reaches about 7.5%. The thin wall exhibited excellent performance in the aeronautical applications owing to the high values of mechanical properties in the room temperature. [ABSTRACT FROM AUTHOR]

Highlights: [•] First systematic study on dissimilar FSW of AA6061 and AA7075 Al alloys. [•] The effects of materials position and welding speed were investigated. [•] All joints failed in HAZ on the AA6061 side where hardness minima is located. [•] The UTS of joints increases with the decrease of heat input. [•] The highest UTS reached 245MPa which is 32% higher than required in AWS standard. [Copyright &y& Elsevier]