You're talking to a person who built a bike others said wouldn't work; yet rode the bike for 10 years. I'm talking about the LandRider which shifted 7 gears automatically.
Maybe you have the equipment to melt down the frame add other metals to change its composition makeup. Otherwise that's something that can't be changed. The bicycle manufacturer chose this metal composition for its reduced weight. It appears to be a beginners to intermediate off-road course bike. The manufacturer didn't choose a metal composition that could withstand a mid-frame engine mount or vibration being sent through it.
There have been several successful aluminium frame builds but these bikes were kept on pavement.