| The aim of this research is to investigate the fracture behavior of iron aluminides under various environments. Comparative crack growth tests of three iron aluminides (Fe-28Al-5Cr, at% with various additives like Zr,C or B) were carried out under air, oxygen or water environment. Moire interferometry was applied to obtain whole-field displacement, crack growth rate, stress intensity factor, and crack-tip strain fields. A digital image processing (DEP) procedure was developed to obtain the strain distributions. Test results showed that the presence of small amount of moisture is sufficient to cause significant embrittlement in iron aluminides. Furthermore, specimens tested in water environment have a very high crack growth rate, indicating that hydrogen-induced embrittlement plays a main role in the mechanical behavior of iron aluminides. The DIP analysis revealed different crack-tip strain distributions and concentrations and correlated well with the intergranular and transgranular fracture modes of the tested alloys. |
