Sun Zhiqian, Song Gian, Sisneros Thomas A, Clausen Bjørn, Pu Chao, Li Lin, Gao Yanfei, Liaw Peter K
Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, USA.
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Sci Rep. 2016 Mar 16;6:23137. doi: 10.1038/srep23137.
An understanding of load sharing among constituent phases aids in designing mechanical properties of multiphase materials. Here we investigate load partitioning between the body-centered-cubic iron matrix and NiAl-type precipitates in a ferritic alloy during uniaxial tensile tests at 364 and 506 °C on multiple length scales by in situ neutron diffraction and crystal plasticity finite element modeling. Our findings show that the macroscopic load-transfer efficiency is not as high as that predicted by the Eshelby model; moreover, it depends on the matrix strain-hardening behavior. We explain the grain-level anisotropic load-partitioning behavior by considering the plastic anisotropy of the matrix and elastic anisotropy of precipitates. We further demonstrate that the partitioned load on NiAl-type precipitates relaxes at 506 °C, most likely through thermally-activated dislocation rearrangement on the microscopic scale. The study contributes to further understanding of load-partitioning characteristics in multiphase materials.
了解各组成相之间的载荷分配有助于设计多相材料的力学性能。在此，我们通过原位中子衍射和晶体塑性有限元模拟，在364和506°C下对多长度尺度的铁素体合金进行单轴拉伸试验，研究体心立方铁基体与NiAl型析出相之间的载荷分配。我们的研究结果表明，宏观载荷传递效率不如埃舍尔比模型预测的高；此外，它还取决于基体的应变硬化行为。我们通过考虑基体的塑性各向异性和析出相的弹性各向异性来解释晶粒水平的各向异性载荷分配行为。我们进一步证明，NiAl型析出相上的分配载荷在506°C时松弛，最有可能是通过微观尺度上的热激活位错重排实现的。该研究有助于进一步理解多相材料中的载荷分配特性。
