A face-centered cubic crystal structure will exhibit more ductility (deform more readily under load before breaking) than a body-centered cubic structure. The bcc lattice, although cubic, is not closely packed and forms strong metals. ... HCP metals like cobalt and zinc are not as ductile as the fcc metals.
Are BCC ductile?
Metals with a body centred cubic (bcc) crystal structure often display ductile/brittle transition properties . Fracture in many bcc metals occurs by brittle cleavage at low temperatures and by ductile tearing at high temperature.
Why is HCP more brittle than BCC?
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.
Is BCC less ductile than FCC?
FCC metals tend to be more ductile than BCC metals because of their different slip systems. ... There are 12 total slip systems, 5 independent. If there are at least 5 independent slip systems, the metal is ductile! BCC crystals have 48 slip systems but still only 5 are independent.
Why are HCP metals less ductile?
There are 3 slip directions for this slip plane, so that the hcp-lattice has a total of 3 slip systems. ... The hcp-lattice thus has only a small ductility compared to the fcc-lattice and the bcc-lattice. Even in the hcp-lattice, additional slip planes can be activated by greater force.
Is HCP stronger than BCC?
BCC metals are less ductile but stronger , eg iron, while HCP metals are usually brittle.
Is BCC a steel?
Steels have been so important to engineers for so many years that each phase has inherited a name as well as a Greek letter. The phase diagrams for steels are on p24 of your book. ... Ferrite is a common constituent in steels and has a Body Centred Cubic (BCC) structure [which is less densely packed than FCC].
Do all metals work harden?
Alloys not amenable to heat treatment, including low-carbon steel, are often work-hardened . Some materials cannot be work-hardened at low temperatures, such as indium, however others can be strengthened only via work hardening, such as pure copper and aluminum.
What is the difference between fcc and bcc?
The terms BCC and FCC are used to name two different arrangements of crystalline structures. BCC stands for body-centred cubic structure whereas FCC stands for face-centred cubic structure. ... The key difference between BCC and FCC is that the coordination number of BCC is 8 whereas the coordination number of FCC is 12 .
How many slip systems are in HCP?
Hence, the h.c.p. structure exhibits three distinct slip systems . 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). Hexagonal close packed crystals slip on <100>{001} slip systems.
Why bcc structure is harder than FCC?
The BCC structure is slightly less closely packed than FCC or HCP and is often the high temperature form of metals that are close-packed at lower temperatures. ... When the metal is deformed, the planes of atoms must slip over each other, and this is more difficult in the BCC structure.
Which structure is stronger BCC FCC?
Yes the APF is important, the atomic packing factor, that is the reason FCC has more slip systems, because of the way the atoms are arranged in the crystal. Thus FCC metals deform easier than BCC metals and thus they are more ductile. BCC metals are infact stronger than FCC metals.
Is FCC ductile or brittle?
The fcc lattice is both cubic and closely packed and forms more ductile materials . Gamma-iron, silver, gold, and lead have fcc structures. Finally, HCP lattices are closely packed, but not cubic. HCP metals like cobalt and zinc are not as ductile as the fcc metals.
What is malleability and ductility?
Malleability and ductility are related. A malleable material is one in which a thin sheet can be easily formed by hammering or rolling. In other words, the material has the ability to deform under compressive stress . ... In contrast, ductility is the ability of a solid material to deform under tensile stress.
Are FCC metals ductile?
The fcc lattice is both cubic and closely packed and forms more ductile materials . Gamma-iron, silver, gold, and lead have fcc structures. Finally, HCP lattices are closely packed, but not cubic. HCP metals like cobalt and zinc are not as ductile as the fcc metals.
Why are FCC metals more ductile as compared to BCC metals?
Even though both FCC and BCC have equal number of slip systems present in the structure, FCC is more ductile. Because the slip planes in the FCC structure are of the closest packing . This is not true for BCC. This means that, the %empty space in a plane is higher in BCC.
