Evaluation of microstructure and corrosion performances of friction stir processed Mg-Al/Mg-Li alloys within various physiological environments
碩士 === 國立虎尾科技大學 === 材料科學與工程系材料科學與綠色能源工程碩士班 === 106 === The present study is to investigate the effects of friction stir processing (FSP) on the microstructural features, phase composition, tensile mechanical properties and anti-corrosion performances of AZ91 and LZ91 Mg alloys in simulated body flui...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2018
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| Online Access: | http://ndltd.ncl.edu.tw/handle/3z25sh |
| Summary: | 碩士 === 國立虎尾科技大學 === 材料科學與工程系材料科學與綠色能源工程碩士班 === 106 === The present study is to investigate the effects of friction stir processing (FSP) on the microstructural features, phase composition, tensile mechanical properties and anti-corrosion performances of AZ91 and LZ91 Mg alloys in simulated body fluid (SBF) and Hank’s solution (HBSS). Experimental results show that the γ-Mg17Al12 particles can be uniformly dispersed and dissolved in α-Mg matrix of AZ91 alloy after FSP modification. The grain refining effect during FSP results in the improvement of microhardness and tensile strength of AZ91-FSP specimens. In addition, both of Mg-rich α-phase and Li-rich β-phase of the dual-phase LZ91 alloy are refined and uniformly dispersed after FSP. The microhardness within the stir zone (SZ) is slightly increased, but the tensile strength is decreased for the LZ91-FSP specimens. XRD analysis results show that the preferred orientations of AZ91 and LZ91 alloys are changed after FSP modification. Electrochemical polarization measuring results show that the anti-corrosion resistance is improved for AZ91-FSP and LZ91-FSP specimens. The grain refining effect after FSP can help to reduce the corrosion rate. The corrosion products and surface morphologies of AZ91-FSP and LZ91-FSP specimens after long-term immersion tests are analyzed and observed by XRD and SEM.
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