한국주조공학회

Ni and Ni-Cr porous metals which are estimated to be easy to fabricate by squeeze casting are used as strengtheners for com- posite materials. As a matrix material, Al-7%wtSi-0.3 wt%Mg(AC4C) has been used. In case of Ni/AC4C and Ni-Cr/AC4C composite, 750°C melt temperature and minimum 25 MPa squeezing pressure are needed to produce sound composite mateiials. The observation of interfacial reaction zone at various heat treatment condition showed that solutionizing temperature of above 520°C, the interfacial reaction zone increased proportionally with increasing heat treatment time and reaction products formed 9 interfacial reaction are mainly composed ofAlNi and Al3Ni2 phases. The tensile strength ofNi/AC4C and Ni-Cr/AC4C compos- ite is lower than the matrix metal and this can be explained by the brittle intermetallic compounds formed at the interface ofliland Ni-Cr reinforcements. But the properties ofhardness, wear resistance and thermal expansion are better than the matrix due to th strengthening etfectofNi-Cr porous metals.