Science Buddies: "Ask an Expert"

I was preparing 200 grams alloy of Aluminium and Magnesium. Initially, I took 10 grams of Magnesium so that it makes 5 wt% in the alloy. After casting of the alloy. I took the alloy for X ray characterisation and noticed that there is only 3.1 wt% of Magnesium is present in the alloy. Why is there a loss? Is it because of the evaporation losses during casting? If so , Can you state an expression to calculate these evaporation losses ?

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