RESUMEN
In this study, 2205 duplex stainless steel with 12 mm thickness was welded by alternating magnetic field-assisted laser arc hybrid welding. The effect of an alternating magnetic field on the proportion distribution of two phases of the welded joint was investigated. The texture distribution, grain boundary misorientation, and grain size of welded joints were analyzed and characterized. The uniform distribution of alloying elements in the two phases was improved by a 20 mT alternating magnetic field. The diffusion dissolution of Ni and N elements into the γ phase was promoted, which was conducive to the transition from the α to γ phase and reduced the precipitation of Cr2N, such that the ratio of γ to α was 43.4:56.6. The ratio of the two phases of the weld was balanced by the alternating magnetic field of 30 mT, such that the ratio of γ and α was 44.6:55.4 and the texture dispersion was weakened. The Σ3 twinning boundary of the austenite phase in the weld was transformed to HABs, the ferrite phase underwent dynamic recrystallization, and the austenite phase had a cube texture, copper texture, and goss texture.
RESUMEN
Si3N4 ceramics and 304 stainless steel were brazed by Ti40Zr25B0.2Cu amorphous solder, and the interfacial microstructure of brazed joint Si3N4 ceramics/Ti40Zr25B0.2Cu/Cu/Ti40Zr25B0.2Cu/304 stainless steel was analyzed. The mechanical properties of the brazed joint were overtly affected by the brazing temperature and Cu foil thickness. The results revealed that the interface structure of the brazed joint might be 304 stainless steel/FeTi/Cu-Zr+Cu-Ti+Fe-Ti/Cu(s,s)/Cu-Zr+Cu-Ti+Fe-Ti/Ti-Si+Zr-Si/TiN/Si3N4 ceramics. The four-point bending strength of the brazed joint decreased sharply as the brazing temperature increased and reached a maximum of 76 MPa at 1223 K. Furthermore, as the Cu foil thickness was increased from 500 µm to 1000 µm, the joint strength rose to 90 MPa at 1223 K.
RESUMEN
The precipitation sequence of a Cu-Ni-Be alloy is: α-Cu supersaturated solid solution â Guinier-Preston (G.P.) zones â metastable γⳠâ γ' â stable γ (NiBe) phase. The micro-hardness and electrical conductivity during the aging process were measured. The precipitation characteristics and the distribution of the γⳠphase, under peak aging conditions, were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area diffraction pattern (SADP), and high-resolution transmission electron microscopy (HRTEM). The results show that the orientation relationship of the γ'' phase/α-Cu matrix is: (001)p//(001)α; [100]p//[110]α (p: Precipitates, α: α-Cu supersaturated solid solution), which is in accordance with the Bain relationship in a FCC/BCC (face centered cubic/body centered cubic) structure, with the unique habit plane being {001}α. While the zone axis is parallel to [001]α, three forms of γⳠphases are distributed on the projection surface at the same time. The (001) reciprocal-lattice positions of γ'' phase in SADP are diffusely scattered, which is consistent with the variation of the d(001) value of the γ'' phase. The intra-range variation is related to the distortion of the (001) plane of the γⳠphase, due to interfacial dislocations and distortion strain fields. The lattice of the γⳠphase in the HRTEM images was measured as a = b = 0.259 ± 0.002 nm and c = 0.27â»0.32 nm. With the increase of thermal exposure time, the stable γ phase has a NiBe phase structure (Standard Card Number: PDF#03-1098, a = b = c = 0.261 nm), and the long diffuse scattering spots will transform into single bright spots. The edge dislocation, generated by interfacial mismatch, promotes the formation of an optimal structure of the precipitated phase, which is the priority of growth in the direction of [110]p.
