Point defects and their properties in FeAl and FeSi alloys

The stress anomaly in FeAl–Fe3Al alloys

“…Fig. 5 shows a summary of vacancy formation enthalpy values from very many research studies [39,40,[42][43][44]46,48,49,[60][61][62][63][64][65][66][67] as a function of Al content. Data has here been separated into three domains, following the ideas of Hehenkamp and workers [63,65], and according to the phase diagam proposed by Kubaschewski [68].…”

Embedded atom method study of the interactions between point defects in iron aluminides: Double defects

“…The development of new, more ductile, Fe-Al alloys depends on a thorough understanding of their properties, implicating a better comprehension of the properties and behaviour of defects in these materials. Experimental [3][4][5] as well as theoretical studies [6][7][8][9][10][11] suggest that iron aluminides present complex point defects, especially double defects. In addition, it has been demonstrated that 'quenched-in' vacancies are responsible for a large strengthening effect both on B2 FeAl [12] and on disordered (A2) Fe-Al alloys [13,14].…”

The internal friction peaks correlated to the relaxation of atomic defects in Fe47Al53 alloy

“…For the rapidly cooled specimens, the P1 peak is much higher in the heating measurements than in the subsequent cooling because most of the thermal vacancies have been annihilated during the heating process. On the other hand, the observation that the P1 peak height increases with increasing quenching temperature or decreases with ageing is also consistent with the changes of vacancies because the higher the quenching temperature, the higher the vacancy concentration or the longer the ageing, the lower is the vacancy concentration [29,35]. However, there is still a certain amount of thermal vacancies which generated at high temperature are retained at room temperature even by slow cooling [14,36].…”

“…Since vacancy formation entropy, which also influences vacancy concentration, cannot be proven to be about constant [27], it is understandable to believe that the vacancy concentration increases with increasing Al content. In addition, it has been reported that the migration energy of vacancies in Fe 61 Al 39 alloy is 1.7 AE 0.2 eV [28], and it increases with increasing Al content in B2 FeeAl alloys [29,30], comparable to the activation energy of the P1 peak. It is therefore concluded that the P1 peak should arise from the migration of the V Fe , which is also supported by the fact that the height of the peak in the rapidly cooled specimens is much higher than that in the slowly cooled ones because the former has more vacancies than the latter.…”