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In order to relieve high residual stresses between ceramics and metals during brazing processes, an AgCuTi/graphene-reinforced Cu foam composite filler was developed and used to braze the ZrB 2 -SiC ceramic and Inconel 600 alloy. Microstructures and shear strengths of the joints were systematically studied. The joints are composed of TiFe 2 , TiCu, TiC, Cu(s, s), Ag(s, s), and Ti 5 Si 3 phases. It is found the addition of graphene on the Cu foam surface can effectively retard diffusions of metal atoms and avoid the collapse of the foam matrix. After being brazed at 900 °C, the joint can get a maximum shear strength of 157 MPa, much higher than those brazed without graphene addition. The high shear strength was investigated in detail and attributed to the integrity of the Cu foam, formation of the TiC and thickness of the reaction layer at the ceramic side. [ABSTRACT FROM AUTHOR]

Abstract In this paper, brazing behaviors between ZrB 2 SiC and Ti 6Al 4V by Cu foam interlayer were studied. The microstructure, formation mechanism, mechanical property and fracture surface of the joints were systematically studied. The results showed that the phases in the joints were α + β -Ti, TiCu, Ti 2 Cu, Cu(s, s), TiC, TiB 2 and Ti 3 SiC 2. An optimum shear strength reached up to 435 MPa at a brazing temperature of 910 °C and holding time of 20 min. Such a shear strength was 90 MPa higher than the one without the Cu foam. The obtained high shear strength of joint was discussed from microstructure and residual stress. With the increase of brazing time, Cu(s,s) gradually disappeared and the content of Ti 2 Cu intermetallic compound increased, which was harmful for the joint. Furthermore, the residual stress of joint with Cu foam was calculated to be 324 MPa, lower than the one without Cu foam interlayer. [ABSTRACT FROM AUTHOR]

The surface treatment of Ti80 alloy with different microstructures was performed by laser shock peening (LSP), and the effect of LSP on Ti80 alloy on microstructure and corrosion properties was investigated. After LSP, the surface grains of Ti80 alloy with different microstructures were all refined, microhardness was significantly increased, and compressive residual stress was generated, and both microhardness and compressive residual stress showed gradient change characteristics along the layer depth. The corrosion resistance of Ti80 alloy with different microstructures was improved in both 3.5% NaCl solution and 5MHCL solution after LSP. Before LSP, the corrosion resistance of lamellar microstructure was the best, followed by bimodal microstructure and the worst by equiaxial microstructure, while the corrosion resistance of equiaxial microstructure exceeded that of bimodal microstructure under the combined effect of volume fraction of β phase, thickness of α phase and compressive residual stress after LSP. • A large number of dislocation tangles and deformation twins were formed in LSPed Ti80 alloy. • LSP can effectively improve the corrosion resistance of Ti80 alloys. • Corrosion resistance of untreated Ti80 alloy: lamellar > bimodal > equiaxial • After LSP, corrosion resistance of Ti80 alloy: lamellar > equiaxial > bimodal [ABSTRACT FROM AUTHOR]

In this work, supersonic fine particle bombardment (SFPB) was applied to modify surface of TC11 alloy and its impacts on microstructure and fatigue properties were systematically studied. The modified surface owned a nanoscale grain structure and a compressive residual stress with an amplitude of −196 MPa. The depth of hardened layer was about 300 μm. Afterwards, high-cycle fatigue behavior of SFPB modified alloy at −30 °C, 25 °C and 150 °C was studied, and the fracture surface, microstructure evolution, residual stress relaxation and microhardness of Ti alloy were characterized. The results show that the fatigue strength of the alloy is significantly improved by SFPB, and the fatigue strength decreases with the testing temperature. The deformation-induced martensite appears in the subsurface structure of Ti alloy tested at 25 °C and 150 °C, and the amount of deformation-induced martensite increases with the fatigue loading temperature. The compressive residual stress field induced by SFPB is relaxed in different degrees during fatigue loading. The degree of residual stress relaxation is the lowest under fatigue loading at 150 °C due to low cycle life. Mechanisms leading to the microstructural evolution and mechanical property variations were also proposed. • Surface nanocrystallization of TC11 alloy can be induced by SFPB. • SFPB can improve the fatigue strength of the TC11 alloy at different temperatures. • Deformation-induced martensite appears in the subsurface layer at 25 °C and 150 °C, but not at −30 °C. • Relaxation degree of residual stress is the lowest after fatigue loading at 150 °C. [ABSTRACT FROM AUTHOR]