Microstructure and properties of Cu–Ti–Ni alloys

Abstract

The effects of Ni addition and aging treatments on the microstructure and properties of a Cu–3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; the hardness, electrical conductivity, and elastic modulus of the resulting alloys were also tested. The results show that Ni addition increases the electrical conductivity and elastic modulus, but decreases the hardness of the aged Cu–3Ti alloy. Within the range of the experimentally investigated parameters, the optimal two-stage aging treatment for the Cu–3Ti–1Ni and Cu–3Ti–5Ni alloy was 300°C for 2 h and 450°C for 7 h. The hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–1Ni alloy were HV 205, 18.2% IACS, and 146 GPa, respectively, whereas the hardness, electrical conductivity, and elastic modulus of the Cu–3Ti–5Ni alloy were HV 187, 31.32% IACS, and 147 GPa, respectively. Microstructural analyses revealed that β′-Ni3Ti and β′-Cu4Ti precipitate from the Cu matrix during aging of the Cu–3Ti–5Ni alloy and that some residual NiTi phase remains. The increased electrical conductivity is ascribed to the formation of NiTi, β′-Ni₃Ti, and β′-Cu₄Ti phases.

Keywords

copper alloys / aging / microstructure / hardness / electrical conductivity / elastic modulus

References

[1] Xie G.L., Wang Q.S., Mi X.J., Xiong B.Q., Peng L.J. The precipitation behavior and strengthening of a Cu-2.0wt% Be alloy. Mater. Sci. Eng. A., 2012, 558, 326.

[2] Soffa W.A., Laughlin D.E. High-strength age hardening copper-titanium alloys: redivivus. Prog. Mater. Sci., 2004, 49(3–4): 347.

[3] Markandeya R., Nagarjuna S., Satyanarayana D.V.V., Sarma D.S. Correlation of structure and flow behavior of Cu-Ti-Cd alloys. Mater. Sci. Eng. A, 2006, 428(1–2): 233.

[4] Lebreton V., Pachoutinski D., Bienvenu Y. An investigation of microstructure and mechanical properties in Cu-Ti-Sn alloys rich in copper. Mater. Sci. Eng. A, 2009, 508(1–2): 83.

[5] Sobhani M., Mirhabibi A., Arbi H., Brydson R.M.D. Effects of in situ formation of TiB2 particles on age hardening behavior of Cu-1wt% Ti-1wt% TiB2. Mater. Sci. Eng. A, 2013, 577, 16.

[6] Markandeya R., Nagarjuna S., Sarma D.S. Characterization of prior cold worked and age hardened Cu-3Ti-1Cd alloy. Mater. Charact., 2005, 54(4–5): 360.

[7] Nagarjuna S., Srinivas M., Balasubramanian K., Sarma D.S. On the variation of mechanical properties with solute content in Cu-Ti alloys. Mater. Sci. Eng. A, 1999, 259(1): 34.

[8] Božic D., Dimcic O., Dimcic B., Cvijovic I., Rajkovic V. The combination of precipitation and dispersion hardening in powder metallurgy produced Cu-Ti-Si alloy. Mater. Charact., 2008, 59(8): 1122.

[9] Markandeya R., Nagarjuna S., Sarma D.S. Effect of prior cold work on age hardening of Cu-4Ti-1Cr alloy. Mater. Sci. Eng. A, 2005, 404(1–2): 305.

[10] Nagarjuna S., Babu U.C., Ghosal P. Effect of cryo-rolling on age hardening of Cu-1.5Ti alloy. Mater. Sci. Eng. A, 2008, 491(1–2): 331.

[11] Nagarjuna S., Balasubramanian K., Sarma D.S. Effects of cold work on precipitation hardening of Cu-4.5 mass% Ti alloy. Mater. Trans. JIM, 1995, 36(8): 1058.

[12] Markandeya R., Nagarjuna S., Sarma D.S. Influence of prior cold work on age hardening of Cu-Ti-Zr alloys. Mater. Sci. Technol., 2005, 21(10): 1171.

[13] Nagarjuna S., Balasubramanian K., Sarma D.S. Effect of Ti additions on the electrical resistivity of copper. Mater. Sci. Eng. A, 1997, 225(1–2): 118.

[14] Markandeya R., Nagarjuna S., Sarma D.S. Precipitation hardening of Cu-Ti-Cr alloys. Mater. Sci. Eng. A, 2004, 371(1–2): 291.

[15] Markandeya R., Nagarjuna S., Sarma D.S. Precipitation hardening of Cu-3Ti-1Cd alloy. J. Mater. Eng. Perform., 2007, 16(5): 640.

[16] Markandeya R., Nagarjuna S., Sarma D.S. Precipitation hardening of Cu-4Ti-1Cd alloy. J. Mater. Sci., 2004, 39(5): 1579.

[17] Markandeya R., Nagarjuna S., Sarma D.S. Effect of prior cold work on age hardening of Cu-3Ti-1Cr alloy. Mater. Charact., 2006, 57(4–5): 348.

[18] Konno T.J., Nishio R., Semboshi S., Ohsuna T., Okunishi E. Aging behavior of Cu-Ti-Al alloy observed by transmission electron microscopy. J. Mater. Sci., 2008, 43(11): 3761.

[19] Semboshi S., Konno T.J. Effect of aging in hydrogen atmosphere on electrical conductivity of Cu-3at.%Ti alloy. J. Mater. Res., 2008, 23(2): 473.

[20] Kikuchi M., Takahashi M., Okuno O. Elastic moduli of cast Ti-Au, Ti-Ag, and TƖ-Cu alloys. Dent. Mater., 2006, 22(7): 641.

[21] Fujiwara K., Tanimoto H., Mizubayashi H. Elasticity study of very thin Cu films. Mater. Sci. Eng. A, 2006, 442(1–2): 336.