The environment at crack tip and its effect on the crack growth behaviour of low alloy steel-E690 steel were studied at cathodic potentials in artificial seawater.The results showed that the micro environment at crack...The environment at crack tip and its effect on the crack growth behaviour of low alloy steel-E690 steel were studied at cathodic potentials in artificial seawater.The results showed that the micro environment at crack tip and crack growth behaviour were related to the electrochemical reactions at crack tip,which were affected by the stress state and applied potentials.The crack tip environment was acidified under cyclic loading,resulting from the crack tip anodic dissolution reaction and corresponding hydrolysis reaction.Because of the hydrogen evolution and the inhibited anodic dissolution inside the crack,the crack tip p H increases as the cathodic potential decreases.The effect of cathodic potentials on the electrochemical reactions caused the variation of the hydrogen content,which influenced the crack growth rate because the crack growth behaviour was controlled by hydrogen embrittlement mechanism.This resulted in a fact that with the negative decrease of potential,the crack growth rate first decreased and then increased,with the minimum rate at-0.75 V.And the crack growth path exhibited transgranular fracture.展开更多
According to the scaling idea of local slope, we investigate numerically and analytically anomalous dynamic scaling behaviour of （1＋ 1）-dimensional growth equation for molecular-beam epitaxy. The growth model inclu...According to the scaling idea of local slope, we investigate numerically and analytically anomalous dynamic scaling behaviour of （1＋ 1）-dimensional growth equation for molecular-beam epitaxy. The growth model includes the linear molecular-beam epitaxy （LMBE） and the nonlinear Lai-Das Sarma-Villain （LDV） equations. The anomalous scaling exponents in both the LMBE and the LDV equations are obtained, respectively. Numerical results are consistent with the corresponding analytical predictions.展开更多
An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with...An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with theconstant rate kernels In（n = 1,2, 3）. Meanwhile, a monomer birth of an A species aggregate of size k occurs under the catalysis of a B species aggregate of size j with the catalyzed birth rate kernel K（k, j） = Kkj^v, and a monomer death of an A species aggregate of size k occurs under the catalysis of a C species aggregate of size j with the catalyzed death rate kernel L（k, j） = Lkj^v, whcre v is a parameter reflecting the dependence of the catalysis reaction rates of birth and death on the size of catalyst aggregate. The kinetic evolution behaviours of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A species ak （t） is found to be dependent crucially on the competition between the catalyzed birth and death of A species, as well as the irreversible aggregation processes of the three species： （i） In the v 〈 0 case, the irreversible aggregation dominates the process, and ak（t） satisfies the conventional scaling form; （2） In the v ≥ 0 casc, the competition between the catalyzed birth and death dominates the process. When the catalyzed birth controls the process, ak（t） takes the conventional or generalized scaling form. While the catalyzed death controls the process, the scaling description of the aggregate size distribution breaks down completely.展开更多
基金the Open Fund of Shandong Key Laboratory of Corrosion Science(No.KLCS201909)the National Natural Science Foundation of China(Nos.51771028,51871024 and 51601182)。
文摘The environment at crack tip and its effect on the crack growth behaviour of low alloy steel-E690 steel were studied at cathodic potentials in artificial seawater.The results showed that the micro environment at crack tip and crack growth behaviour were related to the electrochemical reactions at crack tip,which were affected by the stress state and applied potentials.The crack tip environment was acidified under cyclic loading,resulting from the crack tip anodic dissolution reaction and corresponding hydrolysis reaction.Because of the hydrogen evolution and the inhibited anodic dissolution inside the crack,the crack tip p H increases as the cathodic potential decreases.The effect of cathodic potentials on the electrochemical reactions caused the variation of the hydrogen content,which influenced the crack growth rate because the crack growth behaviour was controlled by hydrogen embrittlement mechanism.This resulted in a fact that with the negative decrease of potential,the crack growth rate first decreased and then increased,with the minimum rate at-0.75 V.And the crack growth path exhibited transgranular fracture.
基金supported by the Fundamental Research Funds for the Central Universities (Grant No. 2010LKWL04)the Youth Foundation of China University of Mining & Technology,China (Grant No. 2008A035)
文摘According to the scaling idea of local slope, we investigate numerically and analytically anomalous dynamic scaling behaviour of （1＋ 1）-dimensional growth equation for molecular-beam epitaxy. The growth model includes the linear molecular-beam epitaxy （LMBE） and the nonlinear Lai-Das Sarma-Villain （LDV） equations. The anomalous scaling exponents in both the LMBE and the LDV equations are obtained, respectively. Numerical results are consistent with the corresponding analytical predictions.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10275048 and 10305009)the Zhejiang Provincial Natural Science Foundation of China (Grant No 102067)
文摘An aggregation growth model of three species A, B and C with the competition between catalyzed birth and catalyzed death is proposed. Irreversible aggregation occurs between any two aggregates of the like species with theconstant rate kernels In（n = 1,2, 3）. Meanwhile, a monomer birth of an A species aggregate of size k occurs under the catalysis of a B species aggregate of size j with the catalyzed birth rate kernel K（k, j） = Kkj^v, and a monomer death of an A species aggregate of size k occurs under the catalysis of a C species aggregate of size j with the catalyzed death rate kernel L（k, j） = Lkj^v, whcre v is a parameter reflecting the dependence of the catalysis reaction rates of birth and death on the size of catalyst aggregate. The kinetic evolution behaviours of the three species are investigated by the rate equation approach based on the mean-field theory. The form of the aggregate size distribution of A species ak （t） is found to be dependent crucially on the competition between the catalyzed birth and death of A species, as well as the irreversible aggregation processes of the three species： （i） In the v 〈 0 case, the irreversible aggregation dominates the process, and ak（t） satisfies the conventional scaling form; （2） In the v ≥ 0 casc, the competition between the catalyzed birth and death dominates the process. When the catalyzed birth controls the process, ak（t） takes the conventional or generalized scaling form. While the catalyzed death controls the process, the scaling description of the aggregate size distribution breaks down completely.
