Investigation the solidification of Al-4.8 wt.%Cu alloy at different cooling rate by computer-aided cooling curve analysis

Abstract

Depending on the casting conditions and alloy composition, microstructure and properties of the aluminium alloys will be different. There are many techniques available for investigating the solidification of metals and alloys. In recent years computer-aided cooling curve analysis (CA-CCA) has been used to determine thermophysical properties of alloys, latent heat and solid fraction. The aim of this study was to investigate the effect of cooling rate on the structural features of Al-4.8 wt.%Cu alloy by thermal analysis of cooling curves. To do this, Al-4.8 wt.%Cu alloy was melted and solidified applying 0.04, 0.42, and 1.08 °C/sec cooling rates. The temperature of the samples was recorded using a K thermocouple and a data acquisition system connected to a PC. It was found that the formation temperatures of various thermal parameters such as (liquidus, solidus and eutectic temperatures) are shifting by increasing of cooling rate from 0.04 °C/sec to 1.08 °C/sec. The structural results show that grain size and secondary dendrite arm spacing decreased by increasing of cooling rate.

Cooling curve analysis in binary Al-Cu alloys: Part I- Effect of cooling rate and copper content on the eutectic formation

“…First deviation is related to the formation of primary dendrites which is followed with their growth and coarsening, and then, second deviation which is due to -Al 2 Cu non-equilibrium eutectic transformation, which occurs in final stages of solidification. With respect to thermal analysis results, it can be said that in this two alloys, final structure contains dendritic phase and -Al 2 Cu non-equilibrium eutectic [3,4]. However, in this figure and for 2.2 wt.% alloy, it can be seen that the second deviation is missed in its cooling curve.…”

“…The temperature of the samples was recorded by a K-type thermocouple with the wire diameter of 0.15 mm placed at the center of the sample and an Advantech 4718 data acquisition system connected to a personal computer. In order to assure the good contact between the thermocouple and the melt, quartz sheathed with an external diameter of 2.5 mm was used [4]. Each trial was repeated three times.…”

“…Backerud [3], found that Al-Cu alloys start to solidify through the development of a dendritic network followed by a eutectic reaction in the interdendritic regions by means of which the eutectic Al 2 Cu is formed in combination with the remaining aluminum. With further decrease in temperature, the Al 2 Cu phase precipitates from the α-phase [2,4]. The thermal analysis is widely used in the evaluation of processing of aluminum alloys because it can provide several pieces of information regarding the alloy.…”

Grain size control in al-4.8 wt.% Cu alloy by computeraided cooling curve analysis

“…First inflection point on the curves results from the evolution of the heat of solidification of the  Al . At the second step at low temperatures, however, solidification is followed by a eutectic reaction [9]. During solidification two phenomena occur simultaneously, i.e.…”

“…In recent years computer-aided cooling curve analysis (CA-CCA) has been used to determine thermo-physical properties of alloys, latent heat and solid fraction. Being very simple to setup it can be widely used, especially in industries [9][10][11]. It just needs to place a thermocouple in the melt and allow the melt to solidify while the temperature is recorded as a function of time.…”