3. true or false (one point each) For the same material with allotropic behavior
ID: 494523 • Letter: 3
Question
3. true or false (one point each)
For the same material with allotropic behavior of BCC and FCC, like Fe, it has a larger mass density when it takes a close-packed crystal structure, like FCC, than when it takes a loose-packed crystal structure, like BCC.
True ______ or False ______
For the same material with an allotropic behavior of BCC and FCC, like Fe, the larger interstitial site (tetrahedral) in BCC is larger than the larger interstitial site (octahedral) in FCC.
True ______ or False ______
FCC and HCP have the same atomic packing density but the former has many more easy slip systems. Thus, FCC materials have larger ductility than HCP materials in general.
True ______ or False ______
For a dislocation, a normal stress is to drive it to slide.
True ______ or False ______
Two similar elements in terms of atomic radius, crystal structure, electronegativity and valence, have a high mutual solubility in each other.
True ______ or False ______
Explanation / Answer
Solution:
1. True as closed packing gives more room for Fe ion packing as iron is dense more Fe ions gives more mass in closed packing than in loose packing hence FCC is more dense than BCC
2. True the FCC gives less space for shaping due to close packing while in BCC gives room for complete geometrical pattern.
3. True, because BCC and FCC had more slip system than HCP hence they are more ductile tha HCP
4. False, dislocation happens with the combination of stress-strain and by only means of sliding the dislocation cannot be happened.
5. False, same electronegativity makes the elements to repel against each other hence a minute difference is expected in electronegativity for increased solubility hence the two similar elements with similar listed properties cannot have mutual solubility rate.
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