Answer+Explanation:
Titanium ( in place of iron)
Titanium could be an excellent replacement for iron when it comes to tensile strength versus weight. It would be the first choice as a building material metal and building skeletons/bridges would use titanium instead of iron.
Magnesium alloys (in place of aluminum)
Magnesium alloys potentially met the present demands for lighter and reliable construction. With comparable specific stiffness, higher specific strength and energy absorption magnesium alloys have the potential to replace steel and aluminum alloys.
aluminum (in place of copper)
Most non-copper metal cabling is aluminum, and it is often used in areas where copper is not a likely alternative. However, it is used more now as a replacement than it has ever been. It is cheaper than copper, and its relative density allows for more cable to be made from a ton of aluminum than a ton of copper.
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