TY - JOUR
T1 - High-pressure torsion of aluminum with ultrahigh purity (99.9999%) and occurrence of inverse Hall-Petch relationship
AU - Ito, Yuki
AU - Edalati, Kaveh
AU - Horita, Zenji
N1 - Funding Information:
One of the authors (KE) thanks Kyushu University for the Qdai-Jump Research grant (No. 28325 ) and the MEXT , Japan, for a Grant-in-Aid for Scientific Research (B) (No. 16H04539 ). This study was supported in part by the Light Metals Educational Foundation of Japan, and in part by a Grant-in-Aid for Scientific Research (S) from the MEXT, Japan (No. 26220909 ). The HPT process was carried out in the International Research Center on Giant Straining for Advanced Materials (IRC-GSAM) at Kyushu University.
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2017/1/2
Y1 - 2017/1/2
N2 - Severe plastic deformation through the high-pressure torsion (HPT) method was applied to pure aluminum with a wide range of purity levels such as 99% (A1100), 99.5% (A1050), 99.99% (4NAl), 99.999% (5NAl) and 99.9999% (6NAl). The hardness of 6NAl decreased with straining and saturated to a level below the hardness level of the annealed sample. This softening behavior, which was similar to the behavior of metals with low melting temperatures such as indium, tin, lead and zinc, was not observed in 5NAl or less pure Al. It was found that the grain-size dependence of hardness became less significant with increasing the purity level, while the HPT-processed 6NAl followed an inverse Hall-Petch relationship. In 6NAl with large grain sizes, dislocations accumulated in the grains in the form of dislocation cells and enhanced the hardness, but when the grain size was small, the dislocations moved fast and disappeared in high-angle grain boundaries.
AB - Severe plastic deformation through the high-pressure torsion (HPT) method was applied to pure aluminum with a wide range of purity levels such as 99% (A1100), 99.5% (A1050), 99.99% (4NAl), 99.999% (5NAl) and 99.9999% (6NAl). The hardness of 6NAl decreased with straining and saturated to a level below the hardness level of the annealed sample. This softening behavior, which was similar to the behavior of metals with low melting temperatures such as indium, tin, lead and zinc, was not observed in 5NAl or less pure Al. It was found that the grain-size dependence of hardness became less significant with increasing the purity level, while the HPT-processed 6NAl followed an inverse Hall-Petch relationship. In 6NAl with large grain sizes, dislocations accumulated in the grains in the form of dislocation cells and enhanced the hardness, but when the grain size was small, the dislocations moved fast and disappeared in high-angle grain boundaries.
UR - http://www.scopus.com/inward/record.url?scp=84992371972&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84992371972&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2016.10.066
DO - 10.1016/j.msea.2016.10.066
M3 - Article
AN - SCOPUS:84992371972
SN - 0921-5093
VL - 679
SP - 428
EP - 434
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
ER -