Size-affected single-slip behavior of Rene N5 microcrystals

作者：Shade P A^*; Uchic M D; Dimiduk D M; Viswanathan G B; Wheeler R; Fraser H L

来源：Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2012, 535: 53-61.

DOI：10.1016/j.msea.2011.12.041

• Size effect
• Microcompression
• Nickel-based superalloys

Microcompression testing was conducted on the cast single crystal nickel-base superalloy Rene N5. Microcrystals were selectively fabricated from either dendrite core or interdendritic regions. The compression axis was oriented for single-slip deformation and microcrystal diameters ranged from 2.5 to 80 mu m. All microcrystals displayed several hallmarks of size-affected plastic flow, including a size-affected and stochastic flow-stress and initial strain hardening rate, as well as an intermittent flow response. The magnitude of size-affected flow-stress scaling behavior was dependent upon the plastic strain level of the flow-stress measurement, with increasing size-dependence for increasing strain levels. TEM analysis demonstrated the activation of multiple slip-systems, despite the microcrystals being oriented for single-slip deformation. Zig-zag slip was also observed in microcrystals that achieved flow stresses of 1300 MPa or higher. For microcrystals fabricated within interdendritic regions the flow-stress values are, on average, lower compared to dendrite core microcrystals. This difference in flow-stress is especially pronounced for microcrystals which are 5 mu m in diameter. The microcrystal diameter for which bulk-like properties are estimated to be observed is approximately 350 mu m, which is approaching the measured primary dendrite arm spacing for this crystal (430 mu m). Published by Elsevier B.V.

• 出版日期2012-2-15