Formation Mechanism of Diffusion Welded Joint

2011 ◽  
Vol 228-229 ◽  
pp. 666-671 ◽  
Author(s):  
Ho Sung Lee ◽  
Jong Hoon Yoon ◽  
Woo Hyun Cho
Keyword(s):  
Formation Mechanism ◽  
Welded Joint ◽  
Boundary Migration ◽  
Welding Process ◽  
Diffusion Welding ◽  
Solid State Diffusion ◽  
Grain Boundary Migration ◽  
Void Closure ◽  
Inert Environment ◽  
State Diffusion

In this study, solid state diffusion welding behavior of titanium alloys was investigated. Formation mechanism of diffusion welding process in six stages is proposed, which is based on cavitation process. The specimens were diffusion welded at elevated temperature under a hydrostatic pressure in an inert environment and the results confirmed the formation mechanism at each corresponding stage. This includes clear evidence of void closure and grain boundary migration at the final stage.

Solide State Diffusion Bonding of Al6061-SiC Nanocomposites

2021 ◽  
Vol 18 (4) ◽  
pp. 9305-9311
Author(s):  
W. Melik ◽  
Z. Boumerzoug ◽  
F. Delaunois
Keyword(s):  
Mechanical Properties ◽  
Composite Material ◽  
Solid State ◽  
Diffusion Bonding ◽  
Welded Joint ◽  
Diffusion Welding ◽  
Solid State Diffusion ◽  
X Ray Diffraction ◽  
X Ray ◽  
State Diffusion

Aluminium matrix composites are both strong and lightweight, and are limited in their applications due to the proper choice of welding process. Conventional welding that is based on fusion at the welded joint is not suitable because it leads to the formation of certain defects at the welded joint. For this reason, solid-state welding such as diffusion bonding is one of the suitable joining methods, as there will be no melting of any of the constituents. The solid-state diffusion bonding at 520° C of Al6061-SiC nanocomposites was investigated. This composite material was made by powder metallurgy, where aluminium alloy Al6061 was selected as the base metal, and SiC nanoparticles with an average size of 50 nm were added as reinforced particles. The effects of bonding time on the microstructures and mechanical properties of the welded material were investigated. The main characterisation techniques were optical microscopy, scanning electron microscopy coupled with energy dispersive spectroscopy, x-ray diffraction, and microhardness measurements. We have found that increasing the holding time up to 3 h at 520° C strengthens the weldability of the two basic composite materials and increases their hardness. X-ray diffraction analysis did not reveal any new phase during diffusion welding; it is considered one of the advantages of using the solid-state diffusion welding technique for the assembly of this kind of composite material. The welding success of this composite material widens its field of use, such as the automotive or space industry, because it is a light material with high mechanical properties.

Solid State Diffusion Welding by Superplastic Coordinate Deformation between Vacuum Spray Fusing Alloy G111WC and Steel Substrate

2007 ◽  
Vol 551-552 ◽  
pp. 399-403 ◽  
Author(s):  
Yao Zong Zhang ◽  
Jian Bo Huang ◽  
H.P. Wang ◽  
X. Lin
Keyword(s):  
Solid State ◽  
Solid Phase ◽  
Steel Substrate ◽  
Strain Ratio ◽  
Alloy Layer ◽  
Diffusion Welding ◽  
Solid State Diffusion ◽  
State Diffusion ◽  
Superplastic State ◽  
Is Strain

This paper discusses the issues about the incorruptibility of industrial dies, mainly researches the G111WC and G112WC mixed alloy layer sprays fusing on the surface of industrial dies under the vacuum condition and the solid phase welding-on mechanism of the mixed alloy layer under superplastic state. It points out that when W≈1 ( W is strain ratio of coating and substrate ) and within the range of the generatrix’s superplasticity, the layer and the generatrix will realize the solid state diffusion joining by superplastic coordinate deformation, which leads to an effective welding.

Solid state diffusion welding by superplastic coordinate deformation between NiFeCrBSi(G112WC) and 3Cr2W8VA

1997 ◽  
Vol 42 (7) ◽  
pp. 605-608 ◽  
Author(s):  
Yaozong Zhang ◽  
Yanxiang Li ◽  
Fuxiao Chen ◽  
Jinliang Huang
Keyword(s):  
Solid State ◽  
Diffusion Welding ◽  
Solid State Diffusion ◽  
State Diffusion

scholarly journals About the possibility of application of laser vacuum welding for the integration of elements of heat-protective structures from powder materials

2021 ◽  
pp. 88-99
Author(s):  
Walid Alnusirat ◽  
Alexandr Salenko ◽  
Olga Chencheva ◽  
Sergii Shlyk ◽  
Irina Gusarova ◽  
...  
Keyword(s):  
Thermal Loading ◽  
Welded Joint ◽  
Local Heating ◽  
High Vacuum ◽  
Welding Process ◽  
Honeycomb Structure ◽  
Diffusion Welding ◽  
Powder Materials ◽  
Thin Elements ◽  
Heat Shielding

The results of studying the process of laser vacuum welding of elements of heat-shielding panels made of heat-resistant dispersion-strengthened powder materials Ni-20Cr-6Al-Ti-Y2O3 of increased strength are presented. Such materials can be used to create ultralight heat-shielding panels, which are systems integrated on the surface of aircraft from typical modules of a cellular structure. Technical solutions of heat-insulating modules are considered, which are a cellular (honeycomb) structure consisting of two plates with a thickness of 0.1 to 0.14 mm, inside which there is a thin honeycomb filler. It is shown that the small thickness of the plates and the complexity of integrating the elements into a single system significantly impair the formation of a strong connection of such elements and do not allow the direct use of the known methods of diffusion welding or vacuum brazing. It has been established that laser welding of elements of heat-shielding structures in vacuum provides satisfactory strength of the structure of the heat-shielding element as a whole. Local heating at certain points prevents deformation of the parts to be joined during the welding process. The use of a pulsed Nd:Yag laser with a power of 400–500 W, operating in the frequency range of 50–200 Hz, allows welding with or without a filler powder. It was found that the use of filler additives practically does not affect the mechanical properties of the welded joint, however, it reduces the melt zone, while increasing the density of the welded joint. Based on the results obtained, it was concluded that it is possible to use laser vacuum welding for the integration of thin elements of heat-shielding modules. It is shown that a satisfactory joint strength is achieved by ensuring high cleanliness of the surfaces of elements before welding, maintaining a high vacuum (less than 10–2 Pa) and rational thermal loading of the surfaces of the elements to be integrated. The use of the proposed process makes it possible to obtain a stronger and denser seam in comparison with the known methods of soldering multicomponent powder dispersion-strengthened materials

Modeling void closure in solid-state diffusion bonding of TC4 alloy

Vacuum ◽  
2020 ◽  
Vol 173 ◽  
pp. 109120 ◽  
Author(s):  
Lin Yuan ◽  
Jiangtao Xiong ◽  
Yu Peng ◽  
Zhenzhen Li ◽  
Jinglong Li
Keyword(s):  
Solid State ◽  
Diffusion Bonding ◽  
Solid State Diffusion ◽  
Void Closure ◽  
State Diffusion ◽  
Tc4 Alloy

Measurement of solute segregation to grain boundaries in the AEM: A review

1988 ◽  
Vol 46 ◽  
pp. 606-607
Author(s):  
D. B. Williams ◽  
A. D. Romig
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Boundary Misorientation ◽  
Collector Plate ◽  
Segregation Process ◽  
Grain Boundary Misorientation ◽  
Structure Boundary ◽  
Equilibrium Segregation

The segregation of solute or imparity elements to grain boundaries can occur by three well-defined processes. The first is Gibbsian segregation in which an element of minimal matrix solubility confines itself to a monolayer at the grain boundary. Classical examples include Bi in Cu and S or P in Fe. The second process involves the depletion of excess matrix solute by volume diffusion to the boundary. In the boundary, the solute atoms diffuse rapidly to precipitates, causing them to grow by the ‘collector-plate mechanism.’ Such grain boundary diffusion is thought to initiate “Diffusion-Induced Grain Boundary Migration,” (DIGM). This process has been proposed as the origin of eutectoid transformations or discontinuous grain boundary reactions. The third segregation process is non-equilibrium segregation which result in a solute build-up around the boundary because of solute-vacancy interactions.All of these segregation phenomena usually occur on a sub-micron scale and are often affected by the nature of the grain boundary (misorientation, defect structure, boundary plane).

Domain coarsening by grain boundary migration in ordered Ni4Mo

1986 ◽  
Vol 44 ◽  
pp. 560-561
Author(s):  
K. Vasudevan ◽  
H. P. Kao ◽  
C. R. Brooks ◽  
E. E. Stansbury
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Short Range ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Rapid Cooling ◽  
Temperature Range ◽  
Fee Structure ◽  
Domain Coarsening ◽  
Boundary Reaction

The Ni4Mo alloy has a short-range ordered fee structure (α) above 868°C, but transforms below this temperature to an ordered bet structure (β) by rearrangement of atoms on the fee lattice. The disordered α, retained by rapid cooling, can be ordered by appropriate aging below 868°C. Initially, very fine β domains in six different but crystallographically related variants form and grow in size on further aging. However, in the temperature range 600-775°C, a coarsening reaction begins at the former α grain boundaries and the alloy also coarsens by this mechanism. The purpose of this paper is to report on TEM observations showing the characteristics of this grain boundary reaction.

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