Microstructure and Mechanical Properties of Al-Ni Alloys by Cold Rolling

Al-Ni alloy has a very fine rod-like Al₃Ni eutectic structure that is chemically stable and has good thermal properties up to 400 °C. Moreover, this alloy has good castability. However, the cold rolling process is another method next to the casting process that can also increase the mechanical properties of the alloy. Therefore, this research studies the microstructure and mechanical properties of hypoeutectic aluminum-nickel alloys (Al-4Ni alloy) produced by the cold rolling process. The experiment starts with the casting of aluminum containing 4% nickel, which is then cold rolled to reduce the thickness from 10 mm to 1.5 mm at room temperature. The optical microscope was used to analyze the microstructure of the alloy. Subsequently, the mechanical properties, i.e., hardness and tensile strength, were tested. From the as-cast microstructure, hypoeutectic Al-4Ni alloys have a microstructure consisting of primary aluminum dendrite structure (α-Al) and the Al-Al₃Ni eutectic structure. The results revealed that after the cold rolling process, both the primary α-Al and eutectic colony elongated in the rolling direction. The mechanical properties in terms of hardness and tensile strength of the Al-4Ni alloy were increased, while the elongation of the Al-4Ni alloy decreased accordingly.