The effect of cooling rate and composition on the secondary dendrite arm spacing during solidification. Part I: Al-Cu-Si alloys

Al-Cu-Si alloys of six different compositions have been solidified by means of the Differential Thermal Analysis (DTA) method. On the basis of the mea surement results it is stated that the secondary dendrite arm spacing (lamb da (2,f)) can be determined with suitable accuracy as a function of the com position (C-0,C-Cu; C-0,C-Si), using the local solidification time (t(f)) o r the cooling rate ((T) overdot(L)) by means of the following equations: la mbda (2,f) = 34.9 X C-0,Cu(-0.333) X C-0,Si(-0.145) X (t(f))(0.208); lambda (2,f) = 77.09 X C-0,Cu(-0.1989) X C-0,Si(-0.078) X ((T) overdot(L))(-0.252 ).