Wires utilized for wire saws may typically be made of relatively high ductility steel, which may be deep drawn down to achieve relatively fine wire diameters in the range of 120 to 380 μm, including all values and increments therein. The lower limit in wire diameter may be limited by the number and practicality of stages of conventional wire drawing, and the ability to achieve relatively significant ductility which may be reduced from work hardening. Additionally, the wires produced may develop a wire drawing texture which results in anisotropic properties. The wire may be used in wire cutting saws, which may include two different varieties: slurry abrasive or diamond wire.
However, some drawbacks exist. For example, in diamond wire cutting, a steel wire may be used as a base which is then built-up by coating with an electrolytic copper sheath, which may be impregnated with diamonds that are typically 10 μm to 120 μm in size. The entire wire may then be coated with a nickel overstrike to reinforce the wire. The build-up of these layers may become a limiting factor in cutting since the total wire diameter may increase to 140 μm to 380 μm. However, the wire thickness contributes to material or kerf loses, which for any relatively high value material including silicon, germanium, gallium arsenide, quartz, glass, etc., the material losses or kerf losses during cutting may be somewhat significant.
While relatively smaller wire diameters may lead to lower kerf losses, as wire diameter decreases, the breaking load (i.e. tensile load) may be reduced dramatically. For example, with reference to FIG. 1, to achieve a breaking load of 30 N (with no factor of safety); the minimum wire diameter necessary may be 80 μm if the wire material had a high tensile strength of 6 GPa. Thus, from purely a strength perspective, the reduced cross sectional area of lower wire diameters may be an overriding factor limiting the commercial implementation of reduced cross sectional wires. Additionally, somewhat heavily drawn wires, may exhibit relatively low tensile elongations, which may limit the applicability of the wires as small flaws could nucleate cracks. Cracks may then propagate through the wire due to the low ductility and the lack of an effective plastic zone in front of the crack tip. Both factors may severely limit the ability to produce commercially successful high aspect ratio wire using conventional steel alloys and conventional strengthening/ductility mechanisms.