High Cooling Rate Cells, Dendrites, Microstructural Spacings And Microhardness In A Directionally Solidified Al-mg-si Alloy

Transient unidirectional solidification experiments have been carried out with an Al-3 wt%Mg-1 wt%Si alloy under cooling rates (T) in the range 0.2-45 K/s. A reverse cells > dendrites transition is shown to occur with the high-cooling rate cellular region associated with T > 2 K/s and the dendritic region with T < 0.8 K/s. Experimental growth laws correlating the cellular and dendritic spacings with the cooling rate are proposed. It is shown that the microhardness is directly influenced by both morphologies of the Al-rich matrix and by the relative fractions of Mg2Si and Fe bearing intermetallics that vary differently with the cooling rate.636145149Avazkonandeh-Gharavol, M.H., Haddad-Sabzevar, M., Fredriksson, H., On the microsegregation of Al-Mg alloys by thermal analysis and numerical modeling (2014) J. Alloys Comp., 610, pp. 462-471Lavernia, E.J., Ayers, J.D., Srivatsan, T.S., Rapid solidification processing with specific application to aluminium alloys (1992) Int. Mater. Rev., 37, pp. 1-44Ninive, P.H., Lovvik, O.M., Strandlie, A., Density functional study of the β'' phase in Al-Mg-Si alloys (2014) Metall. Mater. Trans. A, 45 A, pp. 2916-2924Kaygisiz, Y., Marasli, N., Microstructural, mechanical and electrical characterization of directionally solidified Al-Si-Mg eutectic alloy (2015) J. Alloys Comp., 618, pp. 197-203Kashyap, K.T., Murali, S., Raman, K.S., Murthy, K.S.S., Casting and heat treatment variables of Al-7Si-Mg alloy (1993) Mater. Sci. Technol., 9, pp. 189-203Liu, Y.L., Kang, S.B., The solidification process of Al-Mg-Si alloys (1997) J. Mater. Sci., 32, pp. 1443-1447Verma, A., Kumar, S., Grant, P.S., O'Reilly, K.A.Q., Influence of cooling rate on the Fe intermetallic formation in an AA6063 Al alloy (2013) J. Alloys Comp., 555, pp. 274-282Fei, W.D., Kang, S.B., Effects of cooling rate on solidification process in Al-Mg-Si alloy (1995) J. Mater. Sci. Lett., 14, pp. 1795-1797Trivedi, R., Sekhar, J.A., Seetharaman, V., Solidification microstructures near the limit of absolute stability (1989) Metall. Trans. A, 20 A, pp. 769-777Mullins, W.W., Sekerka, R.F., Stability of a planar interface during solidification of a dilute binary alloy (1964) J. Appl. Phys., 35, pp. 444-451Cahn, R.W., Haasen, P., (1996) Physical Metallurgy, p. 2740. , fourth ed. Elsevier AmsterdamFu, H., Geng, X., High rate directional solidification and its application in single crystal superalloys (2001) Sci. Technol. Adv. Mater., 2, pp. 197-204Fu, J.W., Yang, Y.S., Guo, J.J., Tong, W.H., Effect of cooling rate on solidification microstructures in AISI 304 stainless steel (2008) Mater. Sci. Technol., 24, pp. 941-944Lee, J.H., Kim, H.C., Jo, C.Y., Kim, S.K., Shin, J.H., Liu, S., Trivedi, R., Microstructure evolution in directionally solidified Fe-18Cr stainless steels (2005) Mater. Sci. Eng. A, 413-414, pp. 306-311Goulart, P.R., Spinelli, J.E., Cheung, N., Ferreira, I.L., Garcia, A., Cellular growth during transient solidification of hypoeutectic Al-Fe alloys (2009) J. Alloys Comp., 470, pp. 589-599Gunduz, M., Çardili, E., Directional solidification of aluminium-copper alloys (2002) Mater. Sci. Eng. A, 327, pp. 167-185Ferreira, I.L., Lins, J.F.C., Moutinho, D., Gomes, L.G., Garcia, A., Numerical and experimental investigation of microporosity formation in a ternary Al-Cu-Si alloy (2010) J. Alloys Comp., 503, pp. 31-39Spinelli, J.E., Cheung, N., Garcia, A., On array models theoretical predictions versus measurements for the growth of cells and dendrites in the transient solidification of binary alloys (2011) Philos. Mag., 91, pp. 1705-1723Costa, T.A., Moreira, A.L., Moutinho, D.J., Dias, M., Ferreira, I.L., Spinelli, J.E., Rocha, O.L., Garcia, A., Growth direction and Si alloying affecting directionally solidified structures of Al-Cu-Si alloys (2015) Mater. Sci. Technol., , (in press)Rosa, D.M., Spinelli, J.E., Ferreira, I.L., Garcia, A., Cellular/dendritic transition and microstructure evolution during transient directional solidification of Pb-Sb alloys (2008) Metall. Mater. Trans. A., 39 A, pp. 2161-2174Rocha, O.L., Siqueira, C.A., Garcia, A., Cellular/dendritic transition during unsteady-sate unidirectional solidification of Sn-Pb alloys (2003) Mater. Sci. Eng. A, 347, pp. 59-69Kondoh, K., Oginuma, H., Kimura, A., Matsukawa, S., Aizawa, T., In-situ synthesis of Mg2Si intermetallics via powder metallurgy process (2003) Mater. Trans., 44, pp. 981-985Mondolfo, L.F., (1979) Aluminium Alloys: Structure and Properties, , Butterworths LondonCanté, M.V., Brito, C., Spinelli, J.E., Garcia, A., Interrelation of cell spacing, intermetallic compounds and hardness on a directionally solidified Al-1.0Fe-1.0Ni alloy (2013) Mater. Des., 51, pp. 342-346Brito, C., Siqueira, C.A., Spinelli, J.E., Garcia, A., Effects of cell morphology and macrosegregation of directionally solidified Zn-rich Zn-Cu alloys on the resulting microhardness (2012) Mater. Lett., 80, pp. 106-10