Effect of Cooling Rate and Grain Refining Agents on Microstructure Characteristics of Al-Cu Alloys by Computer- Aided Cooling Curve Method
Subject Areas : journal of New MaterialsM. Dehnavi 1 , M. Haddad-Sabzevar 2
1 - کارشناسی ارشد مهندسی مواد، بخش مهندسی مواد، دانشگاه فردوسی مشهد، مشهد، ایران
2 - استاد بخش مهندسی مواد، دانشکده مهندسی، دانشگاه فردوسی مشهد، مشهد، ایران
Keywords: Al-Cu alloys, Thermal Analysis, Grain size, Al-5Ti-1B Grain Refiner, Cooling Curve,
Abstract :
Depending on the casting conditions and alloy composition, microstructure and properties of the aluminium alloys will be different. Generally Al–Ti and Al–5Ti–1B master alloys are added to the aluminium alloys for grain refinement. In recent years computer-aided cooling curve analysis (CA-CCA) has been used extensively in metal casting industry to predict microstructure constituents, grain refinement and to calculate the latent heat of solidification. The aim of this study is to investigate the effect of cooling rate and grain refinement on the microsructural characteristics of Al-Cu alloys by cooling curve analysis. To do this, Al-Cu alloys containing 2.2, 3.7, and 4.8 wt.% Cu were melted and solidified with 0.04, 0.19, 0.42, and 1.08 K/s cooling rates. The temperature of the samples was recorded using a K thermocouple and a data acquisition system connected to a PC. Some samples were Grain refined by Al-5Ti-1B to see the effect of grain refinement on the aforementioned properties. The stractural results show that grain size and secondary dendrite arm spacing decreased by increasing of cooling rate and grain refinement. Thermal analysis results showed that, in a well refined alloy, nucleation will occur in a shorter time, and a undercooling approximately decreases to zero.
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