thermodynamic modelling of interdiffusion in fe-co and fe-ni bonds matej pašák
TRANSCRIPT
THERMODYNAMIC MODELLING OF INTERDIFFUSION
IN Fe-Co AND Fe-Ni BONDS
Matej Pašák
Main term of diffusionMain 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 bondingDiffusion 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 interface without melting.
EXPERIMENTAL PARTEXPERIMENTAL PART
Selected materials for samplesSelected materials for samples
Material Label [wt. %]
Cobalt Co 99.99
Nickel Ni 99.99
interstitial free steel IF Fe - 99.4
austenitic stainless steel 18/10
Fe – 68.81
Cr – 17.7
Ni – 11.11
Experimental samples preparationExperimental samples preparation
Bonding: 7x7mm; 5Kg; 0.1 MPa; 1100°C; 20 hours
Heat treatment ofHeat treatment of samples samples
Simplified diagrams showing annealing conditions of samples
AnnealedAnnealed samplessamples
Annealed at 1000 hours for 1000 °C
Diffusion profileDiffusion profile
Measured diffusion profilesMeasured diffusion profiles
DICTRADICTRA
DIffusion Controlled TRAnsformations
The DICTRA software 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.
Calculated diffusion profilesCalculated diffusion profilesCo Fe
COMPARISONCOMPARISON
700 700 °°CCFe-18Fe-18//1010
CaclucatedCaclucated
MeasuredMeasured
CaclucatedCaclucated
MeasuredMeasured
8800 00 °°CCFe-18Fe-18//1010
CaclucatedCaclucated
MeasuredMeasured
101000 00 °°CCFe-18Fe-18//1010
CaclucatedCaclucated
MeasuredMeasured
101000 00 °°CCFe-Fe-CoCo
CaclucatedCaclucated
MeasuredMeasured
101000 00 °°CCFe-Fe-NiNi
CCONCLUSIONONCLUSIONComparison 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 between measured and calculated
trends seems to be suitable.
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