What results from the presence of an extra half plane of atoms in a crystal?
Some atomic lattice distortion exists around the dislocation line because of the presence of the extra half-plane of atoms. There are regions in which compressive, tensile and shear lattice strains are imposed on the neighboring atoms. Two edge dislocations that have the same sign and the identical slip plane.
In which dislocation a half plane terminates or gets added within a crystal?
Explanation: Edge dislocations are the linear crystalline defects that are formed due to the extra half plane of atoms in the lattice.
In which type of dislocation an extra plane is inserted inside the crystal?
In which type of dislocation an extra plane is inserted inside the crystal? Explanation: The edge defect is simply pictured as an additional half plane of atoms in a lattice. The dislocations are termed a line defect because of the number of defective points created within the lattice along a line.
What is crystal dislocation?
A dislocation is a linear crystallographic defect or irregularity within a crystal structure which contains an abrupt change in the arrangement of atoms. The crystalline order is restored on either side of a dislocation but the atoms on one side have moved or slipped.
What are the effect of presence of dislocation defect on a crystal?
The screw dislocation is more difficult to visualise, but basically comprises a structure in which a helical path is traced around the linear defect (dislocation line) by the atomic planes of atoms in the crystal lattice. The presence of dislocation results in lattice strain (distortion).
Is dislocation a point defect?
2. Modelisation of the interaction between a dislocation and a point defect: a dislocation, which is assumed straight, is situated at a glide plane projected distance ξ from a point defect, situated itself at a height z above the glide plane.
What can be the unit of dislocation density?
The dislocation density, ρd, a type of concentration, is measured by counting the number of dislocation lines that thread a unit area of surface (i.e., #/m2); ρd is also defined in terms of the total dislocation length per unit volume (i.e., m/m3). Dislocations can be imaged in the electron microscope (Fig.
How is dislocation density related to strength?
The interaction between the stress fields of dislocations can impede dislocation motion by repulsive or attractive interactions. As both of these processes are more likely to occur when more dislocations are present, there is a correlation between dislocation density and shear strength.
Is Youngs modulus affected by dislocation density?
They examined the evolution of the dislocation density as a function of the deformation condition and found a reduction in the Young modulus by 4 to 7% if tensile samples are cold-deformed, which means an increase in dislocation density, before testing. …
What material has the highest modulus of elasticity?
diamond
What is GPa in modulus of elasticity?
The stress/strain ratio is referred to as the modulus of elasticity or Young’s Modulus. The units are those of stress, since strain has no units. Engineering materials frequently have a modulus of the order of 109Pa, which is usually expressed as GPa.
What are the factors affecting modulus of elasticity?
What are the Factors Affecting Modulus of Elasticity?
- Natural of material.
- Type of stress which is used to produce the strain.
Which one is more elastic?
Steel is more elastic than rubber. This is explained with the help of Young’s modulus.
What is static modulus of elasticity?
A stress-strain curve is drawn with the help of values of stress and strain obtained. The modulus of elasticity so obtained from actual loading is called static modulus of elasticity. It has been observed that even under short term loading concrete does not behave as an elastic material.
What is the elasticity of concrete?
The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops. Concrete has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due to shrinkage and tension.
What is the modulus of elasticity of concrete?
Ec = Modulus of elasticity of concrete. f’c = Compressive strength of concrete. IS:456 the modulus of elasticity of concrete is 5000√f’c, MPa.
How do you calculate Young’s modulus of concrete?
The compressive strength of the concrete in the particular series was: 41.37; 48.26 and 42.10 MPa, respectively. The Young’s modulus of the concrete was determined by two methods: static modulus by the static compression test and dynamic modulus on the basis of the transverse free vibration frequency.
What is the Young’s modulus of reinforced concrete?
Modulus of elasticity – E : 14 – 41 GPa (2 – 6 x 106 psi)
Why is elastic modulus important for concrete?
The higher the value of the modulus, the stiffer the material is. Thus, comparing a high performance concrete to a normal strength concrete, it is seen that the elastic modulus for high performance concrete will be higher, thereby making it a stiffer type of concrete.
What are the 4 main properties of concrete?
The properties of hardened concrete
- Mechanical strength, in particular compressive strength. The strength of normal concrete varies between 25 and 40 MPa.
- Durability.
- Porosity and density.
- Fire resistance.
- Thermal and acoustic insulation properties.
- Impact resistance.