Properties Evaluation of Copper-Titanium Composites by a Spark Plasma Sintering Process

Abstract

The Copper (Cu) - Titanium (Ti) powders with varying of Ti content(0.3, 0.5, 1, 2, 4, 6, 8 wt.%) were mixed using a horizontal ball milling. The milling process was performed for 6 hrs at 300 rpm. The Cu-Ti composites were fabricated by a spark plasma sintering process at a sintering temperature of 850℃ and heating rate of 30 ℃/min under a pressure of 40 MPa. The relative density of the composites was all densified to more than 99%. The Cu and Ti in the Cu matrix are unstable to exist in a single phase at temperature range of 800-875°C and a Ti content of 4-8 at.% (3.04-6.15 wt.%). Thus, each element is stabilized by forming a secondary phase. The phase of Cu₃Ti was detected upon the Ti content was 4 wt.% or higher, which affected the thermal properties. The thermal conductivity decreased from 262.74 to 46.10 W/m·K according to increase the Ti contents. The Ti present in the heat transfer path in Cu matrix acted as an obstacle to heat diffusion. Furthermore, as the Ti contents increased, the Vickers hardness of Cu-Ti composite increased from 60.19 to 205.20 kg/mm². In contrast, the crystallite size decreased from 66.63 to 22.43 nm. The Ti particles suppressed the grain growth of the Cu matrix, resulting in a decrease in crystallite size, which contributed to the improvement of the mechanical properties.