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Previous issue date: 2015-08-26 / The main objective of this work was to analyze the solutioning and artificial aging heat treatments of aluminum-copper casting alloys, composed of two distinctive copper contents: 2.5% and 3.5%, unidirectionally solidified in an instrumented metal-mold system. Solidification parameters such as solidification velocities, thermal gradients and cooling rates were determined from cooling curves obtained by thermal analysis. Macrostructures and microstructures of ingots were analyzed in relation to parameters such as columnar-equiaxed transition (CET) and the secondary dendrite arm spacing (SDAS). The heat treatments were performed in order to better understand the solutioning and artificial aging processes of copper in the aluminum matrix. The results concerning to the solidification parameters have permitted to obtain expressions for solidification velocities, thermal gradient and cooling rates as a function of examined alloys. Relationship among solidification conditions, structural formation and hardness were also obtained [SDAS=f(TRL); HB=f(SDAS)]. The Al-3.5wt%Cu alloy has show smaller dendritic arm spacing (10%), higher columnar zone (12%), higher hardness in the as-cast condition (8%), as well as better response to the heat treatments than the examined Al-2.5wt%Cu. / O principal objetivo deste trabalho foi analisar a solubiliza??o e envelhecimento artificial da liga alum?nio-cobre, compostas por dois diferentes percentuais de cobre: 2,5%, e 3,5%, solidificadas unidirecionalmente em sistema metal/molde instrumentado. Os principais par?metros de solidifica??o, como velocidades de solidifica??o, gradientes t?rmicos e as taxas de resfriamento foram determinados a partir das curvas de resfriamentos obtidas por an?lises t?rmicas. Foram analisadas as macroestruturas e as microestruturas dos lingotes, em rela??o aos par?metros de transi??o colunar-equiaxial (TCE) e espa?amentos dendr?ticos secund?rios (EDS). Os tratamentos t?rmicos foram realizados com o intuito de compreender melhor o processo de solubiliza??o e envelhecimento do cobre na matriz de alum?nio, definindo quais tempos e temperaturas que otimizam o processo de endurecimento por precipita??o. Os resultados obtidos em rela??o ? cin?tica de solidifica??o permitiram a obten??o de express?es correlacionado as velocidades, os gradientes t?rmicos e as taxas de resfriamento para ambas as ligas. Tamb?m foram obtidas rela??es entre as condi??es de solidifica??o, forma??es estruturais e as durezas nas diferentes etapas [EDS=f(TRL); HB=f(EDS)]. A liga Al-3,5%Cu apresentou menores valores dos espa?amentos dendr?ticos secund?rios (10%), maior comprimento da zona colunar (12%), maiores durezas na condi??o bruta de solidifica??o (8%), bem como melhor resposta aos tratamentos t?rmicos quando comparada ? liga Al-2,5%Cu.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/6348 |
| Date | 26 August 2015 |
| Creators | Ribeiro, Bruno de Rosso |
| Contributors | Santos, Carlos Alexandre dos |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Engenharia e Tecnologia de Materiais, PUCRS, Brasil, Faculdade de Engenharia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | -7432719344215120122, 600, 600, 600, -655770572761439785, 4518971056484826825 |
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