镍基单晶合金压痕蠕变研究

Study on the indentation creep performed on nickel based single crystal superalloys

摘要:

为了探索压痕法确定晶体学蠕变应力指数的可行性，采用晶体塑性理论模型对不同取向镍基单晶合金压痕蠕变行为进行了有限元模型。研究表明晶体学对称性会导致压痕表面应力呈现特定的对称性；晶体取向对压痕蠕变深度及其扩展速率具有显著的影响。通过开展不同载荷下的压痕蠕变模拟，获得相应的稳态压痕深度扩展速率，再通过线性回归的方法可有效获得晶体学蠕变应力指数。本文提出的确定蠕变应力指数的方法不受晶体取向的影响，有望应用于各向异性高温合金蠕变性能评估。

Abstract:

In order to explore the possibility of determining crystallographic creep exponent using indentation method, extensive finite element simulations were carried out on differently oriented nickel based single crystal superalloys by incorporating crystal plasticity theory. The results showed that the crystallographic symmetry led to a certain symmetric distribution pattern of stress, and the crystallographic orientation had a remarkable influence on the indentation depth and its propagation rate. The steady state indentation depth propagation rates under different indentation loads were extracted by extrapolation approach, and the crystallographic creep stress exponent was then obtained by linear regression method. The creep stress exponents determined by this approach were independent of crystallographic orientation, which shed some light on the evaluation of creep properties of anistropic high temperature alloy using indentation method.