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THERMODYNAMIC MODELLING OF INTERDIFFUSION I N Fe-Co AND Fe-Ni BONDS. Matej Pašák. Main term of diffusion.
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THERMODYNAMIC MODELLINGOF INTERDIFFUSIONIN Fe-Co AND Fe-Ni BONDS Matej Pašák
Main term of diffusion Diffusion is movement of mass. Transport particles from a region of higher concentration to one of lower. It is random thermally activated jumping of atoms in a solid. Jumps are bigger than lattice parameter. Interdiffusion is diffusion of atoms of one element into another element.
Diffusion bonding Welding process that faying surfaces are brought into sufficiently close contact using an applied pressure at elevated temperature to allow bond formation by atomic interdiffusion across the joint interfacewithout melting.
Experimental samples preparation Bonding: 7x7mm; 5Kg; 0.1 MPa; 1100°C; 20 hours
Heat treatment of samples Simplified diagrams showing annealing conditions of samples
Annealedsamples Annealed at 1000 hours for 1000 °C
DICTRA DIffusion Controlled TRAnsformations The DICTRAsoftware is based on a numerical solution of the multicomponent diffusion equations. Diffusion simulations are based on assessed kinetic and thermodynamic data, which have been stored in databases.
700 °CFe-18/10 Caclucated Measured
800 °CFe-18/10 Caclucated Measured
1000 °CFe-18/10 Caclucated Measured
1000 °CFe-Co Caclucated Measured
1000 °CFe-Ni Caclucated Measured
CONCLUSION Comparison between the experimental and the calculated diffusion profiles shows they are not the same but very similar. The agreement between measured and calculated trends is better at higher temperatures. For better qualitative description of the results, finding proportional coefficients betweenmeasured and calculatedtrends seems to be suitable.