科研之友
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摘要
In order to improve the thrust-to-weight ratio of the aero-engine, a new technology of the integral blisk has been widely used, but it has brought about a high-risk failure problem at the disk-blade joint zone. Therefore, the molecular dynamics was used to simulate the tensile mechanical properties of the single-crystal/polycrystalline nickel (SPSNi) at the joint zone. At first, the tensile mechanical properties of different crystalline nickel were compared. It is found that the degree of amorphization at the interface after tension is aggravated due to the presence of the single crystal/polycrystalline interface, which easily germinates the cracks and exacerbates the risk of sudden fracture of SPSNi. Then the effects of strain rate and temperature were investigated. In the range of 1?108 s-1 to 2?1010 s-1, the tensile strength of the SPSNi is almost independent on the strain rate. But after exceeding 2?1010 s-1, the tensile strength σb of SPSNi decreases rapidly with the increase of strain rate. This is because at a high strain rate, the fcc atoms of SPSNi rapidly transform into a disordered amorphous structure on a large scale, resulting in a rapid decline in the carrying capacity of SPSNi. So the strain rate of 2?1010 s-1 can be used as the threshold for the tensile deformation of SPSNi. The tensile strength σb of SPSNi decreases linearly with the increase of the temperature. This is because the SPSNi interface misfit dislocation network gradually becomes irregular under the influence of temperature, and the misfit stress decreases with the increase of temperature during plastic deformation stage.
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