2024-03-29T07:28:36Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/755562022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139Low-Temperature Creep at Ultra-Low Strain Rates in Pure Aluminum Studied by a Helicoid Spring Specimen TechniqueShen, JunjieYamasaki, Shigeto1000050080164Ikeda, Ken-ichiHata, SatoshiNakashima, Hideharuopen accesspure aluminumdislocationultra-low strain ratehelicoid spring creep testgrain boundarystress exponent560The creep behavior in pure aluminum has been investigated by helicoid spring creep tests at strain rates, \\dotε, lower than 10−10 s−1 and low temperature ranging from 0.32Tm to 0.43Tm. It was found that the creep behavior in this region depends strongly on grain sizes and impurity concentrations. For high-purity aluminum (5 N Al) with an average grain size, dg>1600 μm, nearly the wire diameter of the spring sample, where the role of grain boundary during creep deformation can be negligible, the stress exponent was n∼5 and the activation energy was Qc=32 kJ/mol. Microstructural observation showed the formation of large dislocation cells (∼10 μm) and tangled dislocations at the cell walls. For high-purity aluminum (5 N Al) with dg=24 μm, the stress exponent was n∼1 and the activation energy was Qc=15 kJ/mol. On the other hand, for commercial low-purity aluminum (2 N Al) with dg=25 μm, the stress exponent was n=2 and the activation energy was Qc=25 kJ/mol. Microstructural observations revealed dislocations emitted from grain boundaries, those dislocations interacting with intragranular dislocations and the formation of dislocation cells in the grains. Based on those experimental results, the low-temperature creep mechanisms in pure aluminum at \\dotε<10−10 s−1 have been discussed.The Japan Institute of Metals日本金属学会2011-07-01engjournal articleVoRhttp://hdl.handle.net/2115/75556https://doi.org/10.2320/matertrans.M20104051345-96781347-5320AA1151294XMATERIALS TRANSACTIONS52713811387https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/75556/1/Low-Temperature%20Creep%20at%20Ultra-Low%20Strain%20Rates%20in%20Pure%20Aluminum%20Studied%20by%20a%20Helicoid%20Spring%20Specimen%20Technique.pdfapplication/pdf1.08 MB2011-07-01