Fabrication of a Cu/TiNi Composite with High Air-Tightness and Low Thermal Expansion

Abstract

Copper alloys exhibit a positive thermal expansion effect, which is undesirable to materials as in service, while TiNi composite materials exhibit negative thermal expansion. In this study, we fabricated a new high-density Cu/TiNi composite with low thermal expansion through electroless deposition and powder metallurgy. Mixed powders of 15% electroless deposited Cu-TiNi composite powders, and 85% prepared Cu powders were cold extruded, vacuum hot press heat-treated, and hot compressed at 900°C for 2 h. The coefficients of thermal expansion of the Cu/TiNi composite at 100°C, 200°C, and 300°C were 13.99 × 10−6/K, 17.28 × 10−6/K, and 17.72 × 10−6/K, respectively. The fabricated Cu/TiNi composite materials showed good air-tightness and negative thermal expansion, so have bright prospects in lead frames and other electrical and electronic applications.