80 likes | 277 Views
A knowledge of the crystal structure of a metallic solid permits computation of its theoretical density through the relationship:. Lecture # 5. DENSITYCOMPUTATIONS—METALS. EXAMPLE: PROBLEM.
E N D
A knowledge of the crystal structure of a metallic solid permits computation of its theoretical density through the relationship: Lecture # 5 DENSITYCOMPUTATIONS—METALS
EXAMPLE: PROBLEM Copper has an atomic radius of 0.128 nm (1.28 A˚ ), an FCC crystal structure, and an atomic weight of 63.5 g/mol. Compute its theoretical density and compare the answer with its measured density. Solution:
Crystallographic Points and Directions • The position of any point located within a unit cell may be specified in terms of its coordinates as fractional multiples of the unit cell edge lengths.
CRYSTALLOGRAPHIC DIRECTIONS • A crystallographic direction is defined as a line between two points, or a vector. • A crystallographic direction is defined as a line between two points, or a vector. • determination of the three directional indices as shown in figure. • The three indices, not separated by commas, are enclosed in square brackets, thus: [uvw]
Locate the following points for the BCC cubic unit cell. ( (1,1,1),(0,1,0) Calculate the radius of an iridium atom given that It has an FCC crystal structure, a density of 22.4 g/cm3, and an atomic weight of 192.2 g/mol