How many slip planes does hcp have?
The h.c.p structure has only two independent slip systems, since any slip on [110](001) can be described entirely as a combination of slip on [100](001) and [010](001).
What kind of planes and directions are preferred for slip?
For easy movement of dislocation, you therefore require small repeat distances between atoms (in other words high atomic density). This condition is best satisfied in closed pack planes since more atoms are stuffed within this plane compared to others. Therefore slip is preferred in closed pack planes.
Can cross slip occur in hcp metals?
In hcp metals, generalized plasticity requires the activation of slip on pyramidal planes, but the structure, motion, and cross-slip of the associated 〈c+a〉 dislocations are not well established even though they determine ductility and influence strengthening.
What determines slip direction?
One slip system have various slip direction. The direction by which the shear stress on the glide plane exceed a critical magnitude is thought to be slip direction of that plane. you can find out the critical magnitude of the shear stress by Schmidt’s law.
Where does slip occur in BCC?
BCC slip occurs on close-packed planes in close-packed directions. There are 4 close-packed directions: [111], ~ 11], (111], and [111] for the (11.0) plane. Close-packed planes in BCC are {lID}, {112}, and {123}.
What are slip systems of bcc fcc and HCP?
Hexagonal close packed crystals Slip in hexagonal close packed (hcp) metals is much more limited than in bcc and fcc crystal structures. Usually, hcp crystal structures allow slip on the densely packed basal {0001} planes along the <1120> directions. This creates a total of three slip systems, depending on orientation.
What is slip direction?
The slip direction is the direction in which the dislocation moves, which is the direction of the Burgers vector for edge dislocations. During slip, the edge dislocation sweeps out the plane formed by the Burgers vector and the dislocation; this plane is called the slip plane.
What are slip systems of BCC FCC and HCP?
Why is HCP more brittle than FCC?
Why are materials with the HCP crystal structure usually more brittle than BCC or FCC metals? The HCP crystal structure has a lower degree of symmetry than cubic crystal structures; this lower symmetry provides fewer active slip systems and, in general, lower ductility in HCP structures.
Why is it that cross slip in bcc and fcc metals is easier than in HCP metals How does this influence the ductility of BCC fcc and HCP metals?
How does this influence the ductility of BCC, FCC, and HCP metals? The cross slips in hexagonal close-packed (HCP) metals are not easy because the slip planes do not intersect. The cross slips in case of face-centered cubic (FCC) and body-centered cubic (BCC) metals are comparatively possible because they intersect.
Why HCP metals are more brittle than fcc and bcc metals?
Hexagonal close packed metals are typically more brittle than FCC and BCC metals because there are fewer slip systems in HCP.
Which is the slip direction of HCP metals?
• The most common slip direction of hcp metals is <1120>, which is the direction of close contact between atoms in the basal plane. The underlying figure shows shear stresses required for several slip systems in Be metals.
What are the slip planes and the slip directions?
Slip Systems The slip planes and directions, combined to called the slip systems, for several common crystals are summarized in Table. The slip directions are the crystallographic directions with theshortest distance between like atoms or ions and the slip planesare usually densely packed planes. Strains Produced by Slip
How does hcp structure have closed packed planes?
HCP structures have closed packed planes. If the first layer at the bottom of the unit cell is the A position, the second layer of three atoms in the center of the unit cell has a choice of B or C. It chooses B. The third layer, ie the top plane of the unit cell, can choose A or C, but chooses So HCP has a stacking sequence of AB AB AB.
Where does slip occur in hexagonal close packed metals?
Slip in hexagonal close packed (hcp) metals is much more limited than in bcc and fcc crystal structures. Usually, hcp crystal structures allow slip on the densely packed basal {0001} planes along the <11 2 0> directions. The activation of other slip planes depends on various parameters, e.g. the c/a ratio.