Both phenomena are explained by interaction effects between carbon diffusion and dislocation velocity which have at this temperature the same order of magnitude.
The different fracture characteristics may be related to the sufficient carbon diffusion and interface toughening at a high rolling temperature.
Based on the experimental results, the role of dislocations and martensite on carbon diffusion and related phase transformation during low-temperature surface carburization was discussed.
A combined grain boundary and grain mesh structure is employed for simulating surface hardening and intergranular cracking resulting from a surface gas/solid carbon diffusion and bulk creep interaction by assuming variations in their strength ratios.
The estimated values of the carbon diffusion coefficient and the activation energy of the process reflect the grain boundary mechanism of carbon diffusion through the interfacial layer.
In addition, as a carbides forming element, tantalum would reduce the carbon diffusion coefficient and slow down the austenitic transformation rate.
We also examined the contact resistance between the stainless steel and carbon diffusion layer before and after polarization.
Without going into the details of the specific chemistry for each catalyst material, graphene nucleation requires a certain carbon surface concentration which is fed by the precursor dissociation and can be balanced by carbon diffusion in to and out from the catalyst subsurface and bulk.
Activation energies of carbon diffusion into martensite and cementite were calculated, which are 64.5 kJ·mol− 1 and 120.7 kJ·mol− 1, respectively.
This model takes into account all the main stages implicated in CNT growth: methane decomposition, metal surface carburization, carbon diffusion, CNT nucleation and growth.
