Phase-field simulation for the growth of Boride (Fe2B) phase from Austenite phase

Summary The present paper describes briefly the development of phase-field simulation for the growth of boride (Fe2B) phase from the austenite phase. In the present work, the problem in defining the free energy of a line compound such as Fe2B is approached by the assumption that it has a parabolic relationship with the boron concentration. An equilibrium condition can be obtained by one set of free energy applied in the present work. On the other hand, evaluation on the effect of temperature on the growth of boride phase using the present model shows that a higher growth of boride phase was found as the temperature increases from 1193K up to 1273K. BORONIZING PROCESS Boronizing is a type of thermo-chemical treatment where boron atom is diffused into the metal substrate during high temperature process to form hard boride structure such as FeB and Fe2B. Normally it is preferable to have single layer of Fe2B on the substrate rather than having these two boride phases. The presence of single or mixed layer of boride coating mainly depends on the condition of boronizing process. In most cases FeB phase is considered to form firstly before Fe2B phase especially for the low temperature process. However, for the case of high temperature process, such as at 950-1100 o C and with the longer boronizing time, single Fe2B boride phase is possible to exist. Beside having higher hardness compared to other types of thermo-chemical treatment products, boronizing product i