Atomic scale simulation of the strain rate and temperature dependence of crack growth and stacking faults in zirconium
Atomic scale simulation of the strain rate and temperature dependence of crack growth and stacking faults in zirconium
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DOI：
10.1016/j.commatsci.2022.111220
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发表时间：
2022-04
影响因子：
3.3
通讯作者：
V. Podgurschi;D. King;K. Luo;M. Wenman
中科院分区：
文献类型：
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作者：
V. Podgurschi;D. King;K. Luo;M. Wenman
通过分子动力学模拟研究了单晶锆断裂在基面和柱面上的变形机制。研究了温度（0 ~ 300 K）和应变速率（10 8 ~ 10 10 s−1）的影响。发现裂纹尖端取向对断裂行为有强烈影响。在断裂过程中，基底面出现孪晶（{11 2´1}< 11´26>）和< c+ a>型位错，这些位错随后在锥体I 2层错周围解离为部分位错。在较高的应变速率（10 9和10 10 s−1）下，发生孪晶。棱柱面普遍存在边缘位错（1 3< 1 2 > 10>型），且受温度影响较大。在较高温度下（150和300 K），位错密度增大。与0 K相比，150 ~ 300 K时裂纹进一步扩大，位错远离裂纹尖端，对裂纹的屏蔽作用有限。在基面i2、锥体i1和i2层错处加入碘可降低其形成能，而在棱柱状层错处加入碘可提高其形成能。碘还改变了层错的有利顺序，基底I 2和锥体I 1层错变得更有利，棱柱状层错由最有利到最不利。
Molecular dynamics simulations of single crystal zirconium fracture were performed to study the deformation mechanisms active on the basal and prismatic planes. The effects of temperature (0 to 300 K) and strain rate (10 8–10 10 s− 1) were investigated. Crack tip orientation was found to strongly affect the fracture behaviour. On the basal plane twinning ({11 2 ̄ 1}< 1 1 ̄ 26>) and emission of< c+ a> type dislocations that then dissociated into partial dislocations around pyramidal I 2 stacking faults were seen to occur during fracture. At higher strain rates (10 9 and 10 10 s− 1), twinning occurred. The emission of edge dislocations (1 3< 1 2 ̄ 10> type) was prevalent on the prismatic plane and were found to be strongly affected by temperature. At higher temperature (150 and 300 K), the dislocation density increased. The crack grew further at 150–300 K than at 0 K and the shielding effect of dislocations was limited due to their movement away from the crack tip. The addition of iodine at basal I 2, pyramidal I 1 and I 2 stacking faults was seen to decrease the energy of its formation whereas for the prismatic stacking fault it was found to increase it. The iodine also changed the order of favourability of the stacking faults with basal I 2 and pyramidal I 1 stacking faults becoming much more favourable and prismatic going from most to least favourable.