dc.contributor.advisor | Li, Yanjun | |
dc.contributor.author | Søreide, Hanne-Sofie Marie Scisly | |
dc.date.accessioned | 2018-12-06T15:01:55Z | |
dc.date.available | 2018-12-06T15:01:55Z | |
dc.date.created | 2018-06-25 | |
dc.date.issued | 2018 | |
dc.identifier | ntnudaim:18885 | |
dc.identifier.uri | http://hdl.handle.net/11250/2576491 | |
dc.description.abstract | The research deals with the investigation of the precipitation hardening response of a 6082
aluminium alloy with the application of direct electrical current. An experimental setup
was designed and built to conduct experiments on aging treatments with current applied.
The precipitation kinetics were monitored through measurements of Vickers hardness and
electrical conductivity. Moreover, a collection of heat treated samples were investigated by
transmission electron microscopy(TEM) to carry out quantitative estimates of precipitate
dimensions, number density and volume fraction.
Natural aging with a direct current applied showed accelerated precipitation kinetics for
current densities above 12.5A/mm^2. In addition, a direct current was applied as an
initial natural pre-aging treatment prior to storage and final artificial aging. After two
weeks of storage, the hardness on artificial aging increased with increasing current density
applied during the initial natural aging for current densities above 12.5A/mm^2. The
hardness of samples stored for two-three months after a 60 minutes long initial current
treatment, also exhibited a current density dependency. The effect was negative for middle-range densities (5-12.5A/mm^2) and increased with current densities above 20A/mm^2.
TEM micrographs taken of samples initially aged with 2.5 and 25A/mm^2 before two
months storage suggest that the precipitates coarsened with the higher current density.
However, when artificial aging followed directly after 90 minutes of current application at
room temperature, the precipitates formed were smaller in size and of higher number density.
This microstructure was accompanied by a slightly higher hardness in comparison
to the samples treated without current. Application of a current of 2.5A/mm^2 during
artificial aging was observed to accelerate the aging process. The TEM investigations performed at the underaged state showed that the current had resulted in increased number
density and precipitate refinement. | |
dc.language | eng | |
dc.publisher | NTNU | |
dc.subject | Materialteknologi (MTMT), Materialutvikling og -bruk | |
dc.title | Precipitation hardening of a 6082 aluminium alloy upon application of direct electrical current | |
dc.type | Master thesis | |