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In the present study. thermal barrier coatings (TBCs) with two layered bond coat of MCrAlY and MCrAlY-Si were prepared by means of electron beam physical vapor deposition (EB-PVD) on Ni3Al based alloy IC6 in order to suppress the diffusion of Mo contained in the alloy. For the bond coat without Si addition, Mo content near the surface was higher than 7 wt% after isothermal oxidation at 1373 K for 60 h and 12,5 wt% after thermal cycling tested at 1373 K for 300 h (600 cycles). However, in the two layered bond coat with MCrAlY and MCrAlY-Si, only 0.4 wt%, Mo was detected after isothermal oxidation at 1373 K for 100 h and about 0.6 wt% after thermal cycling tested at 1373 K for 400 h (800 cycles). With the use of two layered bond coat of MCrAlY and MCrAlY-Si, the diffusion of Mo was effectively blocked and the thermal cycling behavior of the TBCs has been greatly improved. (c) 2004 Elsevier Ltd. All rights reserved.