Commerical aluminium always contains some magnesium, name two such allous of aluminium. What properties are imparted by the addition of magnesium to these alloys?

Explanation

To answer the question about commercial aluminum containing magnesium, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Two Alloys of Aluminum:**
- The first alloy is **Duralium**.
- Composition: Approximately 92.5% aluminum, 4% nickel, 2% copper, and 1.5% magnesium.
- The second alloy is **Magnelium**.
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