During the heat treatment of Aluminum alloys, two processes: Solution and Precipitation heat treatment were used. Should the hardness increase or decrease from the original alloy after solution heat treatment? My reference text says that the material should be "soft and ductile" after solution heat treatment, but I am not sure if this is accurate. What should be the effect on the hardness after Precipitation heat treatment? I was under the impression that this final hardness should be significantly higher than the original alloy and higher than the hardness measured after solution heat treatment. Thank you.