The effect of preliminary grinding of the charge on the structure and properties of hot-forged heat-resistant alloys of the Nb-Ti-Cr-Al-Mo system

DOI: 10.62564/M4-MM2232

Myroslav Marych, Olena Rokytska, Alex Golubenko

Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine


The development of alloys based on niobium is a promising direction for the creation of heat-resistant alloys with a low specific gravity. Therefore, the task was set to investigate the possibilities of obtaining the alloy by methods of powder metallurgy, in particular hot forging [1-2]. Ti, Al, Mo, Nb, and Cr powders were used as starting materials. 2 types of powder mixtures were formed: without grinding and with preliminary grinding. Grinding of the charge was carried out in a planetary mill for 15 min.Consolidation of powder blanks by the method of hot forging (HF) was carried out on an arc stator press at a temperature of 1200 °C. The annealing of the samples after HF was carried out in a vacuum electric furnace at a temperature of 1600 °C. As a result of the work, powder polycomponent alloys based on niobium were obtained. The technological operation of preliminary grinding of the charge had a significant impact on the microstructure and properties of the alloys. It was established that preliminary grinding of the charge within 15 min. significantly grinds the elements of the structure after hot forging. Porosity decreases due to a more active surface of the particles after grinding. Imaging in the characteristic rays shows that the elements of the alloy are distributed evenly. This indicates a greater degree of diffusion homogenization of the alloy. Grind the mixture of powders for 15 minutes. brings the compressive strength of the hot-forged material closer to the values of the cast one at temperatures up to 800 °С, even with greater porosity of the former. The yield strength of hot forged alloy of NbTiCrAlMo (with grinding) at 800 °С is about 700 MPa, which is almost 2 times more than that of a similar alloy without grinding. Therefore, the production of NbTiCrAlMo alloys by powder metallurgy methods eliminates the problem of element liquation, and preliminary grinding of the charge significantly increases the strength of the obtained alloys.

Keywords
Preliminary grinding, hot forging, element liquation, strength.

Acknowledgments
Not provided

References
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