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|Type of Document
||Work hardening behavior of ultra fine grained commercially aluminum alloy containing nanoscale alumina dispersoids produced by friction stir processing|
|Date of Defense
||friction stir processing
||Al-Al2O3 precipitated alloys and Al-Zn solid solution alloys fabricated by friction stir process are investigated in this study. |
The mechanical specimen cutting from stir zone were tested by Instron machine. Micro-structure was observed by Scanning Electron Microscopy and Transmission Electron Microscopy. Phase composition was measured by X-ray diffraction. Different Grain sizes sample were obtained at condition with constant traverse speed of 1.0mm/s, different RPM(500rpm, 550rpm, 700rpm, 1500rpm and 1500rpm with subsequent annealing treatment) and pin shape. Mechanical properties and ductility improvement on grain size effect are discussed in this research.
In Al/Al2O3 composite materials, mechanical strength is enhanced by Al2O3 precipitation distributed homogeneously in Al matrix and ductility is improved simultaneously by increment of work hardening rate due to interaction between obstacles and dislocations.
In Al-Zn solid solution alloys, ductility enhancement takes place not only in refining grain sizes but also occurs obviously with different weight fraction of Zn addition.
||Kao Po-We - chair|
Chang Liu-wen - co-chair
Ho New-Jin - advisor
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|Date of Submission