1)Dissolving a little (~1 wt%) nickel into otherwise pure copper will decrease t
ID: 2077558 • Letter: 1
Question
1)Dissolving a little (~1 wt%) nickel into otherwise pure copper will decrease the resistivity of the resulting alloy? T / F
2)For a typical semi-crystalline polymer, increasing the percent crystallinity will result in a decrease in yield strengt? T / F
3)Homogeneous nucleation typically requires significantly less undercooling than heterogeneous nucleation? T / F
4)Phase diagrams can be used to predict how quickly a ceramic material can be sintered? T/F
5)A T-T-T curve assumes instantaneous temperature changes while a C-C-T curve assumes temperature changes at constant cooling rates? T/F
Explanation / Answer
1. False ..The existence of impurities and all common alloying elements, except for silver, will decrease the electrical and thermal conductivity of copper so the resistivity increases
2. False. Crystallinty increases both yield strength and stiffness.
3. True
4.True te behaviour of the ceramic during sintering can be fully described in the system phase diagram.
5. False.
TTT diagrams, after cooling to a transformation temperature, you keep the temperature constant until the transformation of austenite to the required transformation product is complete and then cool to the room temperature.
In CCT there is continuous cooling. there is no holding of temperature. The components are cooled at a constant or varying rates. The end products are usually martensite or pearlite depending on the cooling media as well as the material of components.
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