What specific alloy is used for surveying tapes due to its high strength and minimal thermal expansion__________________?
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Answer: E. invar
Explanation
Invar is a specialized nickel-iron alloy featuring an exceptionally low coefficient of thermal expansion across normal temperatures. Surveying tapes demand high dimensional stability to prevent measurement errors caused by ambient temperature fluctuations during fieldwork. The high nickel content stabilizes the crystal lattice structure, neutralizing thermal expansion effects found in ordinary carbon steels. Thermal expansion describes the tendency of matter to change in volume in response to a change in temperature. Alloying iron with approximately thirty-six percent nickel creates invar, renowned for its unique near-zero thermal expansion property. Geodetic surveying requires high-precision instruments that maintain accurate calibration despite changing environmental weather conditions.
Option A mentions silver metal, which expands significantly with temperature and is too costly for general tapes. Option B represents duralumin, a lightweight aluminum alloy used in aviation rather than low-expansion surveying tools. Option C represents Hastelloy, a high-performance nickel alloy designed for corrosion resistance rather than thermal stability.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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