The strength of the ultrafine-grained materials is increased with grain refinement, but it will also reduce the ductility. In the previous study, there are higher strength and better ductility for the copper with bimodal distribution of grain size. In this study, Ni with lamellar structure is fabricated by electrodeposition in order to explore the mechanical properties of the materials with bimodal distribution of grain size, which is obtained by controlling the grain size. From the result of EBSD analysis, it shows that the area ratio of coarse grains and fine grains is from 0.3 to 3 by changing the plating parameters. The average grain size of fine grains is about 0.5 £gm, and the maximum average grain size of coarse grains is up to 6.0 £gm. From the result of tensile test, the materials with 35% of micro-grains embedded regularly inside a matrix of ultrafine grains have better strength and ductility. When the area ratio of micro-grains is up to 62.5%, there is no difference in mechanical properties between the general electrodeposited materials and ones with bimodal distribution of grain size. For pure Ni, the enhancement of ductility for bimodal distribution of grain size is only in post uniform elongation. Otherwise, it is found that the strength and ductility of the material with lamellar structure are increased through the heat treatmeant under the appropriate temperature.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0827112-151750 |
| Date | 27 August 2012 |
| Creators | Gao, Wei-ming |
| Contributors | P. W. Kao, Liuwen Chang, C. P. Chang, J. C. Kuo |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0827112-151750 |
| Rights | user_define, Copyright information available at source archive |
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