Fabrication of thick, crack-free quasicrystalline Al-Cu-Fe coatings by electron-beam deposition

The analysis of the residual stresses dependence on the deposition temperature has enabled the thermal expansion coefficient of the coating material to be determined at αc = (17.1 ± 1.3) ∗ 10− 6 K− 1.The fracture toughness of the coating material in terms of the stress intensity factor has been estimated at K1C=1.68±0.11MPam. These characteristics of the Al-Cu-Fe coatings obtained have been used for the calculation of a critical thickness, below which the crack-free structure of the coatings is retained. The obtained values of the critical thickness were compared with the results of experimental study of surfaces of the Al-Cu-Fe coatings deposited onto different substrates at various temperatures. We observed that the channel cracking was inhibited if the coating was thinner than the corresponding critical thickness.