Mechanical properties and oxidation formation of EB-PVD deposited Ni-Cr-Al alloy
(1.Center for Composite Materials, Harbin Institute of Technology, Harbin 150001, China2.Center for Composite Materials and Structure, Harbin Institute of Technology, Harbin 150001, China)
Abstract: Ni-20Cr-0.6Al（molar fraction, %） alloy sheet with 0.2mm in thickness was deposited at 900℃ from a target of Ni-Cr-Al alloy by EB-PVD. The grain size of as-deposited alloy was less than 100nm. The mechanical properties of alloys were examined using room tensile tests. The ultimate tensile strength of as-deposited and annealed films was 780MPa and 767MPa, respectively. Investigation of fracture surfaces from samples reveals that brittle fracture takes place along boundaries of columnar crystals formed on the substrate side, while the equiaxed dimples are dominant on the evaporation side. Oxide formation of Ni-20Cr-0.6Al alloy after 100h oxidation at 1000℃ in air was studied. The results indicate that a continuous and dense α-Al2O3 scale is formed after 100h oxidation for as-deposited alloy, while a complex oxide scale, consisting of the outer oxide layer of Cr2O3, NiO and NiCr2O4 and the inner oxide layer of Al2O3, forms for annealed alloy.
Key words: EB-PVD； mechanical properties； oxide formation； Ni-Cr-Al alloy