Grain-Size Refinements of Cu-3 mass%Ti Alloys by HDDR Treatments in Correlating with Their Electrical and Mechanical Properties

Abstract

The present paper describes the grain size refinements of Cu-3 mass%Ti alloys by hydrogen heat-treatment of so-called Hydrogenation-Disproportionation-Desorption-Recombination (HDDR) process. During hydrogenation process, the disproportionation reaction occurred with forming of Ti hydrides in the alloy. With decomposition of Ti hydrides by the subsequent desorption process, Ti resolved into Cu matrix. In consequence, the original solid solution phase of the alloys formed. This means that the HDDR phenomena could take place in the Cu-3 mass%Ti alloy. The grain size of the alloy is found to be about 20–50 nm after HDDR treatments such as hydrogenation treatment at 350°C under hydrogen pressure of 7.5 MPa for 48 h, followed by the hydrogen desorption treatment at 530°C for 4 h in vacuum. On the other hand, it is found that remarkable simultaneous improvements of mechanical strength of 1100 MPa and electrical properties of 21%IACS are obtained in the hydrogenated alloy.