. "7"^^ . "Vojt\u011Bch, Dalibor" . "Structural and mechanical stability of the nano-crystalline Ni-Ti (50.9 at.% Ni) shape memory alloy during short-term heat treatments" . . . "In this study, the nano-crystalline Nitinol (50.9 at.% Ni) was prepared by 40% cold deformation. Subsequently it was subjected to 15-min-heat treatments at 300-550 degrees C. Changes of the structure and mechanical properties were studied by transmission electron microscopy, micro X-ray diffraction, differential scanning calorimetry, Vickers hardness measurements, tensile and bend-type fatigue testing. It was shown that the cold drawn material contains textured nano-crystalline B2 grains of 50 nm in thickness and a high concentration of lattice defects. Its tensile strength, hardness and fatigue life were 1521 MPa, 421 HV0.05 and 2435 bending cycles to fracture, respectively. After heat-treatment up to 450 degrees C/15 mm the material underwent Ni4Ti3 precipitation and partial recovery processes. Heat-treatments at above 450 degrees C induced recrystallization, grain and precipitate growth. Hardness and fatigue lives showed maxima of 692 HV0.05 and 5883 cycles, respectively, after heat-treatments at 450 degrees C/ 15 min. In contrast, both tensile strength and B2 -} B19' transformation stress decreased with increasing heat-treatment temperature, but a decrease of the tensile strength after heat-treatments at 300-450 degrees C was slow (tensile strength after heat-treatment at 450 degrees C/15 mm was 1486 MPa). The observed variations of mechanical characteristics were discussed in relation to structural changes observed: (C) 2014 Elsevier Ltd. All rights reserved." . . . "22310" . "49" . . "[24E8C967BB0C]" . "Structural and mechanical stability of the nano-crystalline Ni-Ti (50.9 at.% Ni) shape memory alloy during short-term heat treatments"@en . "In this study, the nano-crystalline Nitinol (50.9 at.% Ni) was prepared by 40% cold deformation. Subsequently it was subjected to 15-min-heat treatments at 300-550 degrees C. Changes of the structure and mechanical properties were studied by transmission electron microscopy, micro X-ray diffraction, differential scanning calorimetry, Vickers hardness measurements, tensile and bend-type fatigue testing. It was shown that the cold drawn material contains textured nano-crystalline B2 grains of 50 nm in thickness and a high concentration of lattice defects. Its tensile strength, hardness and fatigue life were 1521 MPa, 421 HV0.05 and 2435 bending cycles to fracture, respectively. After heat-treatment up to 450 degrees C/15 mm the material underwent Ni4Ti3 precipitation and partial recovery processes. Heat-treatments at above 450 degrees C induced recrystallization, grain and precipitate growth. Hardness and fatigue lives showed maxima of 692 HV0.05 and 5883 cycles, respectively, after heat-treatments at 450 degrees C/ 15 min. In contrast, both tensile strength and B2 -} B19' transformation stress decreased with increasing heat-treatment temperature, but a decrease of the tensile strength after heat-treatments at 300-450 degrees C was slow (tensile strength after heat-treatment at 450 degrees C/15 mm was 1486 MPa). The observed variations of mechanical characteristics were discussed in relation to structural changes observed: (C) 2014 Elsevier Ltd. All rights reserved."@en . "47830" . "000334085800002" . "\u010Capek, Jaroslav" . . "GB - Spojen\u00E9 kr\u00E1lovstv\u00ED Velk\u00E9 Brit\u00E1nie a Severn\u00EDho Irska" . "\u010Derven" . "Structural and mechanical stability of the nano-crystalline Ni-Ti (50.9 at.% Ni) shape memory alloy during short-term heat treatments" . "RIV/60461373:22310/14:43898120" . . "5"^^ . "Dragounov\u00E1, Lenka" . "Michalcov\u00E1, Alena" . "Structural and mechanical stability of the nano-crystalline Ni-Ti (50.9 at.% Ni) shape memory alloy during short-term heat treatments"@en . . "5"^^ . "Biomedical applications; Microscopy various; Microstructure (as-cast. deformation-induced, recrystallization-induced); Heat treatment; Mechanical properties at ambient temperature; Nanostructured intermetallics (including preparation methods)"@en . . . . "P(GBP108/12/G043)" . . . "RIV/60461373:22310/14:43898120!RIV15-GA0-22310___" . "0966-9795" . . . . "Marek, Ivo" . . "10.1016/j.intermet.2013.12.013" . "Intermetalics" . . . . . .