Determination of stress intensity factor of anultra-high strength wire fe78cr3si10b12

Chapter 1
Literature review

1.1 What are metallic glasses?

Amorphous metal alloys and amorphous metals, alloys can be cooled from the liquid or gaseous state, completely suppressing crystallization. They are characterized by ductile, possess high hardness and tensile strength.

The metallurgists are familiar with the term "quenching" which he defines as quenching, its mainpurpose is to control the microstructure to achieve optimum physical properties of the final product.

Through the rapid solidification of metal alloys can be obtained outside of a regular atomic order by freezing liquid or gas structure in the solid state. Many rapid quenching techniques have been developed, but currently the most used is the technique of melt spinning. "This techniqueinvolves injecting a liquid jet or wire onto a substrate, which is usually a copper disc which is rotating at high speed and thus the injected alloy rapidly solidified vitrified. Amorphous metal alloys have high static and dynamic resistance.

1.2 Direct Wire obtaining vitreous

Ohnaka, developed the melt spinning process for the production of wire, using various methods, includinginjection of the metal in ambient air and water. This method uses centrifugal force rather than gravity or mechanical force to achieve laminar flow control of the medium and the liquid metal coolant. It uses an induction coil, which melts the metal in a quartz crucible, once the metal is melted this is injected by pressure exerted by an inert gas (argon) through a nozzle into the cooling layer of waterformed by the action of centrifugal force on the surface of the drum that rotates at very high speeds between 320 and 360 revolutions per minute (rpm). The drum rotation speed controls the cooling rate, while the injection pressure controls the speed of the liquid metal thread. Figure 1.1 shows a photograph of a machine for the manufacture of wires above process. Figure 1.2 shows a diagram ofthe process, which is described as follows: The thread of liquid metal is injected through a quartz nozzle 80 to 200 microns in diameter, within a layer of liquid coolant (water), rotating at a speed of 400 to 600 rpm The quality and continuity of the wire to get are controlled by the rotation of the drum and gas injection pressure.

[pic]
Figure 1.1. Process melt spinning[pic]
Figure. 1.2 Process scheme INROWASP

For continuous wires with uniform surfaces should be strict control of process parameters:
• Material of the crucible.
• Diameter of the nozzle.
• Distance between the nozzle tip and the surface layer of the coolant.
• Angle of injection.
• Depth of water coolant.
• Coolant temperature.
• cooling speeds.• Heat Transfer.
• Value-speed wire speed liquid water.

With this technique has been possible to produce wires with amorphous structure in the following alloy systems:
• Ni-Pd-P
• Ni-Pd-S
• Ni-P-B
• Ni-Si-B-Al
• Ni-P-B-Al
• Ni-Al-Fe
• Fe-P-C
• Fe-Si-RE (rare earth)
• Fe-Cr-Si-B
• Fe-Si-B
• Fe-Ni-Cr-Al-C
• Fe-Mn-Al-C
•Co-Si-B
• Pd-Cu-Si
• Mn-Al-C
• Cu-Zr
• Metal-Zirconium (Metal= Cu, Cu-Nb y Cu-Ta)

The mechanical properties of wires obtained by rapid solidification are comparable to ultra-high strength wire such as piano wire and wire SUS 304, same as Resistance reach a greater than 3 GPa.

Ohnaka, published a list of advantages and disadvantages of producing ultra-high strengthwires by this method.

Advantages:
• Wires completely round.
• You can produce metastable phases.
• The wire is rapidly cooled below room temperature.
• You can produce small diameter wires in compositions that can’t.

Disadvantages:
• Requires a planned process control, primarily when it is within the cooling system.
• There are limits on the range of melting...