High-energy High-speed Consolidation for TZM Alloy Manufacturing

Using hot isostatic for TZM mixed powder pressing due to time temperature deviation large, the mixed powder can be not fully densifying. And it will affect alloy’s mechanical properties. Using high-energy high-speed consolidation technology to replace the hot isostatic for mixed powder pressing, it is possible to produce high-density material and improve alloy’s strength. In this production process, the powder is pressed between the electrodes by means of high voltage which produced by unipolar generator to press the powder. When the voltage is about 25 to 5 volts, the unipolar generator can provide 100-150A/mm2 current density. Using high-energy high-speed consolidation method for TZM alloy powder pressing and the production process is as following:

1. TZM alloy powder was mixed evenly. And in TZM mixed powder the Ti content is 0.47%, Zr 0.109%, carbon 0.018%, oxygen 0.0016%, and average particle size is 74um.

2. The powder was placed in between the electrodes, and the current is about 10 megajoules to make the mixed solidified. During discharge, the copper electrode should to cover with a 250 microns molybdenum foil layer, or directly using tungsten electrodes. Besides, the weight of the powder is between 59 ~ 150g and molding pressure is between 270 to 690 MPa in the regulation.

Using high-energy high-speed consolidation for powder pressing, the powder has high density, moderate strength, low toughness and appropriate structural changes. After sintered, TZM alloy structure is unevenly, mainly because of copper electrode conduction cooling, so the copper electrode will affect the temperature of the powder.

With different pressures and unit input power, the midplane density of alloys is different. When the consolidation energy is higher than 3000 J/g, the densification is much larger than 98%. When consolidation energy is about 270-890 MPa can little affect the results.

TZM image

When the local density is greater than 96%, the alloy shows good mechanical properties. In the sintering process, the alloy exhibits low plasticity, mainly because of the presence of excess oxygen. However, the oxygen content is too small Mo also suffers severe embrittlement.

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