Cooling Rate and Gradient by Fe- and Mn-Rich Phases Precipitation in AlCuSi Alloys

Gravity influences mold filling and solidification. In foundry engineering, apart from well-known gravity, centrifugal and pressure casting, technologies for casting by forced convection are being developed, where the application of a magnetic field plays a key role. Till now, the efficacy of forced flow in numerous studies have been conducted, including silicon extraction and aluminum alloys. The weakness of these studies is the fact, that they were conducted on small samples, mainly cylindrical shaped, where the cooling rate, gradient and temperature field were poorly investigated and discussed. In the present study, , thermal conditions like temperature gradient G and cooling rate R by the growth of occurring phases were studied using numerical simulation, concerning the facility applied in the investigations on the effect of rotating magnetic field. In cylindrical samples from base AlCuSi alloys, cooling rate R and temperature gradient G presented dependence from: calculation method for R and G (specified temperature or solid fraction in the TL-TS range), the place of measurement in the sample and from solid fraction curve determined by the alloy composition. β-Al9Fe2Si2 phases precipitated at G=0.050-0.103 ˚C/mm and R=0.103-0.135 ˚C/s near to liquidus temperature and at G=0.043-0.387 ˚C/mm and R=0.318-0.404 ˚C/s near to solidus in AlCu4Si6Fe1 alloy, whilst at G=0.021-0.225 ˚C/mm and R=0.467-0.475 ˚C/s near to liquidus and at G=0.165-0.284 ˚C/mm and R=0.151-0.862 ˚C/s near to solidus in AlCu10Si10Fe1 alloy. Al15Si2Mn4 phases precipitated at G=0.008-0.281 ˚C/mm and R=0.539-0.552 ˚C/s near to liquidus, whilst at G=0.050-0.322 ˚C/mm and R=0.292-0.356 ˚C/s near to solidus in the AlCu4Si6Mn2 alloy. In the prediction of secondary dendrite arm spacing and AlSi eutectic spacing new approach was tested and appropriate values of materials coefficient’s have been established. Negligible impact of errors in processing parameters set by experimental procedure was observed.