Agradecimentos: The authors would like to thank the Brazilian research funding agencies FAPESP (São Paulo Research Foundation – projects 2009/08478-1, 2013/09961-3 and 2015/22143-3), CNPq (National Council for Scientific and Technological Development – project 470572/2011-6) and CAPES (Federal...

Agradecimentos: The authors would like to thank the Brazilian research funding agencies FAPESP (São Paulo Research Foundation – projects 2009/08478-1, 2013/09961-3 and 2015/22143-3), CNPq (National Council for Scientific and Technological Development – project 470572/2011-6) and CAPES (Federal Agency for the Support and Improvement of Higher Education – notice 23/2016, process 88881.131045/2016-01) for providing financial support for this study. The authors are also indebted to the Faculty of Mechanical Engineering at the University of Campinas and the Faculty of Mechanical Engineering at University of Oriente, and the Federal Institute of Education, Science and Technology of São Paulo – IFSP for the practical support very kindly provided.

The aim of this work was to evaluate the thixoformability of Al-(2 to 7 wt%) Si-Cu alloys by differential thermal analysis (DTA), differential scanning calorimetry (DSC) and CALPHAD simulation. Thermoanalytical data were generated for exothermic (rheocasting) and endothermic (thixoforming) cycles...

The aim of this work was to evaluate the thixoformability of Al-(2 to 7 wt%) Si-Cu alloys by differential thermal analysis (DTA), differential scanning calorimetry (DSC) and CALPHAD simulation. Thermoanalytical data were generated for exothermic (rheocasting) and endothermic (thixoforming) cycles under different kinetic conditions (heating and cooling rates of 5, 10, 15, 20 and 25 degrees C/min). The findings indicate that the SSM critical temperatures and liquid fractions are directly affected by the kinetic conditions, chemical composition and heat-flow direction and that the measured values of these critical temperatures and liquid fractions vary according to the thermodynamic evaluation technique used (Calphad simulation, DSC or DTA). The SSM working window (a) became smaller as the heating/cooling rates and Si content increased; (b) was larger for rheocasting (solidification) than for thixoforming (melting) operations; (c) was on average approximately 12 degrees C wider and covered a range of mass fractions approximately 0.12 greater for DSC measurements than for DTA measurements; and (d) had a low sensitivity for all the conditions analyzed, indicating the thermodynamic stability of the Al-Si-Cu system. CALPHAD simulation successfully predicted several transformations and the thermodynamic behavior of the temperatures and liquid fractions analyzed. The DTA and DSC techniques yielded discrepant results for some of the critical points investigated, such as the limits of the SSM working window. The majority of the DSC cycles were more sensitive to variations in kinetic conditions, heat-flow direction and chemical composition than the corresponding DTA cycles. Furthermore, the tertiary Al2Cu phase transformation could not be identified in many of the DTA cycles. For these reasons, DTA should be used with caution when predicting the thermodynamic behavior of potential raw materials for SSM processing

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ

COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPES

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP

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