The aim of this paper was to attain defect free, pure copper castings with the highest possible electrical conductivity. In this connection, the effect of magnesium additives on the structure, the degree of undercooling (ΔTα = Tα-Tmin, where Tα - the equilibrium solidification temperature, Tmin - the minimum temperature at the beginning of solidification), electrical conductivity, and the oxygen concentration of pure copper castings have been studied. The two magnesium doses have been investigated; namely 0.1 wt.% and 0.2 wt.%. A thermal analysis was performed (using a type-S thermocouple) to determine the cooling curves. The degree of undercooling and recalescence were determined from the cooling and solidification curves, whereas the macrostructure characteristics were conducted based on a metallographic examination. It has been shown that the reaction of Mg causes solidification to transform from exogenous to endogenous. Finally, the results of electrical conductivity have been shown as well as the oxygen concentration for the used Mg additives.
 Górny, Z. (2011). Copper and copper alloys with high conductivity. Cracow: Instytut Odlewnictwa.
 Vincent, C., Silvain, J.F., Heintz, J.M. & Chandra, N. (2012). Effect of porosity on the thermal conductivity of copper processed by powder metallurgy. J. Phys. Chem. Solids. 73, 499-504.
 Chung, W.-H., Hwang, H.-J. & Kim, H.-S. (2015). Flash light sintered copper precursor/nanoparticle pattern with high electrical conductivity and low porosity for printed electronics. Thin Solid Films. 580, 61-70.
 Schlesinger, M.E., King, M.J., Sole, K.C. & Davenport, W.G. (2011). Chapter 20 - Melting and Casting. In Extr. Metall. Copp. (397-413). 5th ed., Elsevier.
 Hsu, Y.T. & O’Reilly, B. (1977). Impurity effects in highconductivity copper. JOM. 29, 21-24.
 Bonderek, Z. & Rzadkosz, S. (2000). The phenomena of porosity in castings made of aluminium and magnesium alloys. Solidif. Met. Alloy. 2, 51-55.
 Lu, L., Shen, Y., Chen, X., Qian, L. & Lu, K. (2004). Ultrahigh Strength and High Electrical Conductivity in Copper. Science. 304, 422-426.
 Habibi, A., Ketabchi, M. & Eskandarzadeh, M. (2011). Nano-grained pure copper with high-strength and highconductivity produced by equal channel angular rolling process. J. Mater. Process. Technol. 211, 1085-1090.
 Romankiewicz, F. (1995). Solidification of Copper and its alloys. Poznań- Zielona Góra: PAN.
 Ẑitňanský M. (1995). Refining of the Copper and investment casting. J. Mater. Process. Technol. 53, 499-507.
 Fu, Y., Chen, J., Liu, N., Lu, Y., Li, T. & Yin, G. (2011). Study of ultrahigh-purity copper billets refined by vacuum melting and directional solidification. Rare Met. 30, 304-309.
 Yamamura, S., Shiota, H., Murakami, K. & Nakajima, H. (2001). Evaluation of porosity in porous copper fabricated by unidirectional solidification under pressurized hydrogen, Mater. Sci. Eng. A. 318, 137-143.
 Lun, S., Sin, A. & Elsayed, C. (2013). Ravindran, Inclusions in magnesium and its alloys: a review, Int. Mater. Rev. 58, 419-436.
 Shahzeydi, M.H., Parvanian, A.M. & Panjepour, M. (2016). The distribution and mechanism of pore formation in copper foams fabricated by Lost Carbonate Sintering method. Mater. Charact. 111, 21-30.
 Li, B.Q. & Lu, X. (2011). The Effect of Pore Structure on the Electrical Conductivity of Ti. Transp. Porous Media. 87, 179-189.
 Cuevas, F.G., Montes, J.M., Cintas, J. & Urban, P. (2009). Electrical conductivity and porosity relationship in metal foams. J. Porous Mater. 16, 675-681.
 Gu, C.F., Hoffman, M., Toth, L.S. & Zhang, Y.D. (2015). Grain size dependent texture evolution in severely rolled pure copper. Mater. Charact. 101, 80-188.
 Miyajima, Y., Okubo, S., Abe, H., Okumura, H., Fujii, T., Onaka, S. & Kato, M. (2015). Dislocation density of pure copper processed by accumulative roll bonding and equalchannel angular pressing. Mater. Charact. 104, 101-106.
 Zi, A. (2010). Pure copper processed by extrusion preceded equal channel angular pressing. Mater. Charact. 61, 141-144.
 Benchabane, G., Boumerzoug, Z., Thibon, I. & Gloriant T. (2008). Recrystallization of pure copper investigated by calorimetry and microhardness. Mater. Charact. 59, 1425-1428.
 Chen, J., Yan, W., Liu, C.X., Ding, R.G. & Fan, X.H. (2011). Dependence of texture evolution on initial orientation in drawn single crystal copper. Mater. Charact. 62, 237-242.
 Han, S.Z., Goto, M., Ahn, J.-H., Lim, S.H., Kim, S. & Lee, J. (2014). Grain growth in ultrafine grain sized copper during cyclic deformation. J. Alloys Compd. 615, S587-S589.
 Han, S.Z., Goto, M., Lim, C., Kim, S.-H. & Kim, S. (2009). Fatigue damage generation in ECAPed oxygen free copper. J. Alloys Compd. 483, 159-161.
 Kuhn, H.-A., Altenberger, I., Käufler, A., Hölzl, H. & Fünfer, M. (2012). Properties of High Performance Alloys for Electromechanical Connectors, in: Copp. Alloy. - Early Appl. Curr. Perform. - Enhancing Process. InTech, p 51-68.
 Konečná, R. & Fintová, S. (2012). Copper and Copper Alloys: Casting, Classification and Characteristic Microstructures, in: Copp. Alloy. - Early Appl. Curr. Perform. - Enhancing Process., InTech, 3-30
 Bydałek, A.W., Bydałek, A. & Czyż, M. (2000). The rational principle of the copper alloys refining. Solidif. Met. Alloy. 2, 65-71.
 Rzadkosz, S., Kozana, J. & Kranc, M. (2013). Researching the Influence of Chemical Composition and Technological Parameters on the Quality of Copper Alloys. Arch. Foundry Eng. 13, 153-158.
 Rzadkosz, S., Kranz, M., Nowicki, P. & Piękoś, M. (2009). Influence of refining operations on a structure and properties of copper and its selected alloys. Arch. Metall. Mater. 54, 299-304
 Baker, H. Ed. (1992). ASM Handbook: Alloy phase diagrams. United States of America: 10th ed., ASM International.