Anisotropy of Poisson’s ratio in single crystal superalloys

J. Q. Zhao1*

1 Beijing Institute of Aeronautical Materials

*zhaojq621@163.com

The anisotropy of Poisson’s ratio is investigated in single crystal superalloys by X-ray diffraction. The dog-bone specimens which is characterized with thin wall are prepared with a series of orientation, such as [001], [011] and [111]along their own axis. The distances of crystal plane both along the axis and transverse directions are measured at the same time by a X-ray diffraction meter with face detector before a random load is imposed on the axis. The accurate strains both along longitudal axis and the designated transverse directions are obtained at once, so the expected Poisson’s ratio is figured out. By means of [001]-[010]-[100], [001]-[110]-[-1 1 0], [011]-[100]-[0 -1 1] and [111]-[11 -2]-[1 -1 0] specmens, whose first direction is referred to the axis and the second referred to that perpendicular to the specimen plane, the main Poisson’s ratios can be obtained. In addition, the [-1 10]-[113]-[33 -2] specimen is prepared, as well as other common indice crytal direction, by which the Poisson’s ratio can be got between [-1 10] and [113], aslo other directions such as between [-1 10] and [115] and so on.

The X-ray diffraction meter with face detector can be used for measurement of single crystal, by which serials of distance of crystal planes can be got, then the spatial Poisson’s ratio. Poisson’s ratio is significant constant of solid materials [1,2]. The variance of strain along different directions implies the deficiency of symmetry to some extent. Those measurements can result in rather intensive comprehension on mechanical behaviour of single crystal superalloy. The research indicates that all the single crystal superalloys possess obvious anisotropic Poisson’s ratios, and there exists some difference between different single crystal superallys.

References

[1] U. Larsen, O. Signund , S. Bouwsta . Journal of Microelectromechanical Systems 1997, 6(2):99-106.

[2] H . Gercek. International Journal of Rock Mechanics and Mining Sciences, 2007, 44(1):1-13.