Diffusion Bonding of Dissimilar Intermetallic Alloys Based on Ti_2AlNb and TiAl

Direct diffusion bonding of an orthorhombic Ti 2 AlNb base alloy to a TiAl base alloy, Ti-22Al-23Nb-2Ta and Ti-46.2Al-2Cr-2Nb-0.15B (at. pct), was carried out and the interface microstructure, formation of new phase at the interface and joint strength were characterized. At low temperature, a new phase with AlNb 2-structure, Al(Nb, Ti) 2 , was formed in the interface region adjacent to the O base alloy. The α 2 was found to be the major reaction product and developed in the interface region adjacent to the ...     

Changing Rule of Carbon-Enriched Zone and Diffusion Behavior of Carbon in Aging 0Cr6Mn13Ni10MoTi/1Cr5Mo Dissimilar Welded Joints

The microstructures, the changing rule of carbon-enriched zone, the diffusion behaviors of elements C and Cr, and thecarbide type of 0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints after aging at 500℃ for various times and afterlong-term service in technical practice were investigated by using the optical microscopy electron probe microanalysis,scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that in aging0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints, the main carbides are M_3C and a few carbides are M_7C_3 andM_(23)C_6. The M_3C carbide decomposition and dissolution with increasing aging time or aging temperature and theanti-diffusion of C and Cr cause the decrease and disappearance of the carbon-enriched zone. The results are differentfrom those of the A302/1Cr5Mo dissimilar welded joints in previous studies.     

XRD and TEM Analysis in the Interface of Diffusion Bonding for Fe3Al/Q235 Dissimilar Materials

Phase structure characteristics near the interface of Fe3Al/Q235 diffusion bonding are investigated by means of X raydiffraction (XRD), transmission electronic microscope (TEM) and electron diffraction, etc. The test results indicatedthat obviously a diffusion transition zone forms near the interface of Fe3Al/Q235 under the condition of heatingtemperature 1050~1100℃, holding time 60 min and pressure 9.8 MPa, which indicated that the diffusion interfaceof Fe3Al/Q235 was combined well. The diffusion transition zone consisted of Fe3Al and a-Fe(Al) solid solution.Microhardness near the diffusion transition zone was HM 480~540. There was not brittle phase of high hardness inthe interface transition zone. This is favorable to enhance toughness of Fe3Al/Q235 diffusion joint.