Cu–4％Ni–2％Si合金における時効析出物のTEM観察

抄録

Cu–Ni–Si alloys have been used for electronic devices such as semiconductor lead frames because Cu–Ni–Si alloys have excellent electrical conductivity and strength. It is well known that Cu–Ni–Si alloys are strengthened by fine precipitates of δ–Ni₂Si (orthorhombic crystal structure) during aging treatment. There are many reports about mechanical properties of Cu–Ni–Si alloys, however, a few papers are dealt with crystal structure evolution of both matrix and precipitates using high resolution transmission electron microscope (HRTEM). In this work, Cu–3.8mol％Ni–1.8mol％Si (42NS) alloy having Ni/Si = 2, were prepared and hardness test and microstructure observation of alloy were performed to investigate the precipitates in high Ni and Si content alloy. In as quenched samples, coarse or fine intermetallic compounds were remained in 42NS alloy. They are mostly identified as δ–Ni₂Si by scanning electron microscope–energy dispersive X–ray spectroscopy (SEM–EDS) technique. In aged samples, fine precipitates were confirmed by TEM and HRTEM observation. Fine precipitates increased with increasing of aging times.