For SHILD & WEIGHT HEAVY ALLOY

Thanks to the above characteristics, Heavy Alloy is used in various fields. For example, because of high density and good machinability, it is used widely as the raw material for weight. Because of high density, it has excellent radiation shielding effect and used as shielding material in X-ray equipment for medical and industrial use. In the application as weight or shielding material, Heavy Alloy has gotten attention as a substitute for lead, which has been used till present but has become a controversial issue in recent years for environmental problems.
Moreover, thanks to its low thermal expansion, excellent mechanical property at high temperature and oxidation resistance, Heavy Alloy is used as the raw material for die-cast mold parts for casting aluminum and copper alloys, and semiconductor parts. As electrode material, it is used for a wire chuck electrode for welding solder-plated copper wire, realizing a much longer life than that of conventional copper alloy electrode.

On the radiation shielding effect of Heavy Alloy, we examined a comparative evaluation with lead. Fig.1 shows the attenuation rate of γ-ray (Co60) against the change in thickness of Heavy Alloy and lead. The γ-ray (Co60) used for the evaluation this time is that eradiated from relatively a high energy zone, which becomes an issue in the case of nuclear power station.
This evaluation proves that Heavy Alloy of about 3mm or 7mm thickness has the radiation shielding effect equivalent to lead of about 4.5mm or 10mm thickness respectively. Consequently, Heavy Alloy, compared with lead, has 1.5 times shielding effect against γ-ray (Co60).

Tungsten is fundamentally a very oxidizable metal. It generates a very thin oxide layer on its surface even at a room temperature and starts oxidizing at about 400�‹C. Heavy Alloy, though consisting mainly of tungsten, has some degree of oxidation resistance and, among Heavy Alloy series, HAX1 (W-Ni-Fe-α) has excellent resistance to oxidation. Fig.2 is the comparison of oxidation increment of HAC1, HAF1 and HAX1 under oxidizing condition (700�‹C x 3hr in air), showing that HAX1 has excellent oxidation resistance. Thanks to this oxidation resistance, Heavy Alloy has been achieving satisfactory results in application to die-cast mold parts and semiconductor parts, which are used under high temperature.

Tungsten is a material having difficulty in machining, especially cutting, so its machining is limited to grinding by use of a diamond wheel, etc. or electro-discharge machining. Although Heavy Alloy mainly consists of tungsten, one of the hardest materials, it can be machined with a cemented carbide tool. According to the application, Heavy Alloy can be machined into various shapes by milling, end-milling, tapping, etc. as shown in Photo 3, Photo 4 and Photo 5.