Creep and anelastic backflow behaviors of pure copper （4N Cu） with grain size dg=40 μm were investigated at low temperatures of T〈0.3Tm （Tm is melting point） and ultra-low creep rates of ε≤1×10^-10 s^-1 b...Creep and anelastic backflow behaviors of pure copper （4N Cu） with grain size dg=40 μm were investigated at low temperatures of T〈0.3Tm （Tm is melting point） and ultra-low creep rates of ε≤1×10^-10 s^-1 by a high strain-resolution measurement （the helicoid spring specimen technique）. Analysis of creep data was based on the scaling factors of creep curves instead of the conventional extrapolated steady-state creep rate. Power-law creep equation is suggested to be the best for describing the primary transient creep behavior, because the pre-parameter does not apparently change with elapsed time. The observed anelastic strains are 1/6 of the calculated elastic strains, and linear viscous behavior was identified from the logarithm plot of the anelastic strain rate versus anelastic strain （slope equals 1）. Therefore, the creep anelasticity is suggested to be due to the unbowing of there-dimensional network of dislocations.展开更多
工业纯钛TA2中低温蠕变行为存在显著的温度及应力相关性。基于外加应力水平和蠕变应变的变化关系,确定不同蠕变温度下的门槛应力水平。根据短时蠕变实验数据,利用包含稳态蠕变速率的本构方程外推稳态蠕变速率,而后进行两组相对长时的蠕...工业纯钛TA2中低温蠕变行为存在显著的温度及应力相关性。基于外加应力水平和蠕变应变的变化关系,确定不同蠕变温度下的门槛应力水平。根据短时蠕变实验数据,利用包含稳态蠕变速率的本构方程外推稳态蠕变速率,而后进行两组相对长时的蠕变实验,证明了工业纯钛中低温蠕变存在稳态蠕变阶段。利用稳态蠕变速率与应力关系,计算出工业纯钛室温蠕变应力指数为6.96,也说明了外推稳态蠕变速率的可靠性。中低温蠕变激活能随着蠕变进行变化不大(≈60 k J/mol),但一直大于以位错为变形主导机制的变形激活能(30~40 k J/mol),表明孪晶对于工业纯钛中低温蠕变发展整个阶段均起重要作用。根据蠕变后试样孪晶结构随温度的变化解释了TA2蠕变行为的温度相关性,同时也证明了孪晶对于TA2蠕变行为的重要性.展开更多
基金Project(12JCYBJC32100)supported by the Tianjin Research Program of Application Foundation and Advanced Technology,ChinaProject([2013]693)supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘Creep and anelastic backflow behaviors of pure copper （4N Cu） with grain size dg=40 μm were investigated at low temperatures of T〈0.3Tm （Tm is melting point） and ultra-low creep rates of ε≤1×10^-10 s^-1 by a high strain-resolution measurement （the helicoid spring specimen technique）. Analysis of creep data was based on the scaling factors of creep curves instead of the conventional extrapolated steady-state creep rate. Power-law creep equation is suggested to be the best for describing the primary transient creep behavior, because the pre-parameter does not apparently change with elapsed time. The observed anelastic strains are 1/6 of the calculated elastic strains, and linear viscous behavior was identified from the logarithm plot of the anelastic strain rate versus anelastic strain （slope equals 1）. Therefore, the creep anelasticity is suggested to be due to the unbowing of there-dimensional network of dislocations.
基金National Natural Science Foundation of China(51475223,51075199)
文摘工业纯钛TA2中低温蠕变行为存在显著的温度及应力相关性。基于外加应力水平和蠕变应变的变化关系,确定不同蠕变温度下的门槛应力水平。根据短时蠕变实验数据,利用包含稳态蠕变速率的本构方程外推稳态蠕变速率,而后进行两组相对长时的蠕变实验,证明了工业纯钛中低温蠕变存在稳态蠕变阶段。利用稳态蠕变速率与应力关系,计算出工业纯钛室温蠕变应力指数为6.96,也说明了外推稳态蠕变速率的可靠性。中低温蠕变激活能随着蠕变进行变化不大(≈60 k J/mol),但一直大于以位错为变形主导机制的变形激活能(30~40 k J/mol),表明孪晶对于工业纯钛中低温蠕变发展整个阶段均起重要作用。根据蠕变后试样孪晶结构随温度的变化解释了TA2蠕变行为的温度相关性,同时也证明了孪晶对于TA2蠕变行为的重要性.
