Aluminum distribution wiring in homes was used for a short time from the mid 1960’s to the late 1970’s. This came about because the price of copper got very high and aluminum was thought to be an economical substitute. By nature copper is a better conductor for electricity which is why you will typically find larger gauge aluminum wires as compared to copper. Electrical receptacles, switches and even electrical panels that were designed for copper wiring are not suitable for aluminum wiring.
There are 3 main differences between copper and aluminum. First is how soft aluminum is compared to copper, aluminum is easily damaged during installation. Second is the expansion of the wires, aluminum expands much more as electricity flows through it which causes loose connections over time. Third is the rusting and/or oxidation of the wires, when copper rusts it is still conductive however when aluminum rusts or oxidises it loses conductivity which creates heat in the wires. Quick things to look at to protect your home with aluminum wiring is to make sure your receptacles, switches, wire connectors and even electrical panels and breakers are rated for aluminum, they will be marked with AL-CU or CO/ALR.
Warning signs to be aware of with aluminum wiring: Warm cover plates, switches or receptacles. Switches or receptacles that inexplicably do not work. Smoke or an inexplicable smell, almost like rotting food or eggs.