Phase transformations in a Cu Cr alloy induced by high pressure torsion

• Published in: Materials characterization 2016-04, Vol.114, p.151-156
• Main Authors: Korneva, Anna, Straumal, Boris, Kilmametov, Askar, Chulist, Robert, Straumal, Piotr, Zięba, Paweł
• Format: Article
• Language: English
• Subjects: ALLOYS; ANNEALING; ANNEALING PROCESSES; Copper base alloys; DECOMPOSITION; GRAIN SIZE; HIGH PRESSURE; MATERIALS SCIENCE; MICROHARDNESS; Microstructure; MICROSTRUCTURES; NANOSCIENCE AND NANOTECHNOLOGY; PARTICLE SIZE; PHASE TRANSFORMATIONS; PHASES; PRECIPITATES; PRECIPITATION; SCANNING ELECTRON MICROSCOPY; SOLID SOLUTIONS; Surface layer; TEMPERATURE RANGE 0273-0400 K; TEMPERATURE RANGE 0400-1000 K; TEMPERATURE RANGE 1000-4000 K; Texture; TEXTURES; Torsion; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2016.02.017

Phase transformations induced by high pressure torsion (HPT) at room temperature in two samples of the Cu-0.86at.% Cr alloy, pre-annealed at 550 degree C and 1000 degree C, were studied in order to obtain two different initial states for the HPT procedure. Observation of microstructure of the samples before HPT revealed that the sample annealed at 550 degree C contained two types of Cr precipitates in the Cu matrix: large particles (size about 500nm) and small ones (size about 70nm). The sample annealed at 1000 degree C showed only a little fraction of Cr precipitates (size about 2 mu m). The subsequent HPT process resulted in the partial dissolution of Cr precipitates in the first sample and dissolution of Cr precipitates with simultaneous decomposition of the supersaturated solid solution in another. However, the resulting microstructure of the samples after HPT was very similar from the standpoint of grain size, phase composition, texture analysis and hardness measurements.