Grain Refinement of Deoxidized Copper

Abstract

This study reports the current status of grain refinement of copper accompanied in particular by a critical appraisal of grain refinement of phosphorus-deoxidized, high residual P (DHP) copper microalloyed with 150 ppm Ag. Some deviations exist in terms of the growth restriction factor (Q) framework, on the basis of empirical evidence reported in the literature for grain size measurements of copper with individual additions of 0.05, 0.1, and 0.5 wt pct of Mo, In, Sn, Bi, Sb, Pb, and Se, cast under a protective atmosphere of pure Ar and water quenching. The columnar-to-equiaxed transition (CET) has been observed in copper, with an individual addition of 0.4B and with combined additions of 0.4Zr-0.04P and 0.4Zr-0.04P-0.015Ag and, in a previous study, with combined additions of 0.1Ag-0.069P (in wt pct). CETs in these B-and Zr-treated casts have been ascribed to changes in the morphology and chemistry of particles, concurrently in association with free solute type and availability. No further grain-refining action was observed due to microalloying additions of B, Mg, Ca, Zr, Ti, Mn, In, Fe, and Zn (~0.1 wt pct) with respect to DHP-Cu microalloyed with Ag, and therefore are no longer relevant for the casting conditions studied. The critical microalloying element for grain size control in deoxidized copper and in particular DHP-Cu is Ag.

Influence of Solute Content on Grain Size in Binary Cu Alloys

“…Discrepancies between grain size and alloying elements at a solute concentration of 0.1 wt% have also been reported by Bustos [24]. Furthermore, equiaxed grain coarsening was observed in the work of Balart et al [13] for several alloying elements. This raises the question which factors affect the low correlation between Q and grain size in Cu alloys.…”

“…where m is the slope of the liquidus line, k is the partition coefficient and c0 is the solute concentration. These parameters can be derived from binary phase diagrams and were given by Cziegler et al [12] and by Balart et al [13]. However, the evaluation of Q based on binary phase diagrams is strongly dependent on the resolution of the respective phase diagram [12].…”

Numerical and Experimental Investigation of the Influence of Growth Restriction on Grain Size in Binary Cu Alloys

“…However, only limited data is given for increasing alloy concentration. Furthermore, grain size was observed to increase for several alloying elements at 0.1 wt %, and no comparison with a valid supercooling parameter (P) or Q were given, as Q-values for Cu alloys have just been recently reported [30][31][32]. This raises the question: can a similar correlation be found for Q and grain size in Cu alloys as has been observed for Al and Mg alloys?…”

Effects of Superheat and Solute Additions on the Grain Size in Binary Copper Alloys

“…Grain refinement of copper and copper alloys has recently attracted the interest of the scientific community [1][2][3][4][5][6][7]. It is worthwhile briefly highlighting previous studies on grain refinement in copper and copper alloys [8][9][10][11][12][13]: in air, in the late 1930s by Northcott [8,9], and in a protective atmosphere of pure Ar (99.997 pct), in the early 1990s by Bustos and Reif [10][11][12][13].…”

“…where m is the slope of the liquidus, c 0 is the solute concentration, and k is the equilibrium distribution coefficient [5].…”