Principal Metallic crystal Structures 0.0 / 5 ? EngineeringPhysics of materialsUniversityNone Created by: OmololaS15Created on: 26-12-18 14:43 Describe the hexagonal close packed structure Base and top layer (A) is a hexagonal shape , B layer (atoms placed in gaps) is in the centre of the structure. 1 of 24 What are the lengths of a and b( sides of the unit cell for HCP)? 2R 2 of 24 What is the distance between the first layer and the second layer (a.k.a |c| in unit cell of HCP) 2(√8/3) R 3 of 24 What is the coordination number?(HCP) 12 4 of 24 What are the atoms per unit cell? (HCP) 2 5 of 24 What are the # lattice points per unit cell ? (HCP) 1 6 of 24 What are the # atoms per lattice points ? (HCP) 2 7 of 24 Describe the face centred cubic structure Atoms at each corner and at the centre of each face. 8 of 24 What is the distance from the centre of one atom to a 3rd atom in the close packing plane? √(2a) = 4R 9 of 24 Describe the dimensions and angles present in an f.c.c structure a=b=c , all angles =α=β=γ= 90° where a = 2√(2R) 10 of 24 What is the coordination number?(f.c.c) 12 11 of 24 What are the atoms per unit cell? (FCC) 4 12 of 24 What are the # lattice points per unit cell ? (FCC) 4 13 of 24 What are the # atoms per lattice points ? (FCC) 1 14 of 24 Describe the body centred cubic structure . Atoms on each corner and one in the centre of the cubic 15 of 24 Describe the dimensions and angles present in an BCC structure a=b=c and all angles =90° where a= 4/√(3) *R 16 of 24 What is the close packed direction for a BCC structure? (if there is such a thing) Only the diagonal from one corner to another passing the centre is a close-st packing direction 17 of 24 Define the atomic packing factor The volume of atoms within the unit cell divided by the volume of the unit cell. 18 of 24 Give an equation for the APF #atoms*volume of 1 atom/ volume of unit cell 19 of 24 What is the APF for BCC structure? 0.68 20 of 24 What is the APF for FCC structure? 0.74 21 of 24 What is the APF for a simple cubic structure? 0.52 22 of 24 What is the close packing direction for an FCC structure? The face diagonals are close-packed directions. 23 of 24 Define Coordination number The bravais lattice points closest to a given point.( The nearest neighbours) 24 of 24
Comments
No comments have yet been made