Which type of alloys exhibit higher thermal expansion coefficients and high solidification shrinkage?

• A. Steel
• B. Copper alloys
• C. Aluminum
• D. Titanium

Answer: (C)

Understanding how materials expand with temperature and how they shrink as they solidify helps predict distortion and casting defects. Aluminum alloys have relatively high coefficients of thermal expansion compared with the other common structural metals, so they expand more when heated and contract more when cooled. They also exhibit noticeable solidification shrinkage, meaning the liquid metal occupies more volume than the solid form and can leave behind shrinkage cavities if feeders and proper design aren't used. These properties together describe aluminum alloys well, explaining why they are associated with both higher thermal expansion and significant solidification shrinkage.