Problem 1: (4 Points+ 4 bomus questions) True (T) or False ( 1. A vacancy is a p
ID: 2087978 • Letter: P
Question
Problem 1: (4 Points+ 4 bomus questions) True (T) or False ( 1. A vacancy is a point defect that is located in an interstintial sine 2. Synthesis and processing affect both structure and properties of 3. Metallic bonding is found only in metals and thcir alloys material 4. FCC metals can have stacking sequence of ABC-ABC closed-packod planes 5. Deformation in which stress and strain are proportional is called elastic strai 6. Inter-diffusion occurs for pure metals by having atoms of the same type exchanging their positions 7. In recovery, some of the stored internal strain energy is relieved mostly due to re-arrangement of dislocation structure upon annealing 8. For a ductile material the fracture surface has the shape of cup-and-cone 9. Tempering of martensite occurs by heating below 200°C for a long time 10. Spheroidite structure occurs by heating the steel alloy to a temperature just below the eutectoid temperature for a very short time 11. For a binary isomorphous alloy, a complete solubility in the solid phase is expected to occur. 12. A line separating a liquid and solid+liquid phase fields is called solidusExplanation / Answer
1: FALSE: vacancy denotes a position vacated by an atom in parent metal lattice. So it is occupied a substitutial site.
2:TRUE: by processing ,macrostructure is changed and due to change in structure properties are changed.
3:TRUE:since metallic bond is formed by partial sharing of valence electrons by neighbouring. In which electron cloud possible in some metals only.
4:TRUE:stacking sequence is arrangement of atomic planes one above the other. In a fcc such a 3 types of planes occurs.
5:FLASE: stress directly proportional to strain upto proportional limit. And the deformation is elastic deformation .
6:TRUE:it occurs between one interstitial site to another
7:TRUE:yes due to dislocation of atoms and due to enhanced diffusion, stored strain energy is relieved.
8:TRUE:because ductile material is weak in shear and this shear failure occurs at 45 and 135 degrees which is cup and cone structure .
9:FALSE:it is done above 200c.because tempering is done to reduce hardness and higher the temperature lower the hardness.
10:TRUE :because to convert it into ductile and machinable.
11:FALSE :completely soluble in liquid state but completely insoluble in solid state.
12:FALSE: Line separating liquid and solid+liquid phase is called liquidus line