Effect of biaxial cyclic severe deformation on structure and properties of Ti-Ni alloys

Deformation Behavior, Structure, and Properties of an Aging Ti-Ni Shape Memory Alloy after Compression Deformation in a Wide Temperature Range

“…A 5-mm-diameter Ti-50.9 at.%Ni alloy rod obtained by hot forging at a temperature of 800°C was used for TMT. As a reference treatment (RT) (as usually applied in comparative studies of similar alloys 4,24,25 ), the samples were annealed at 700°C for 30 min, followed immediately by cooling in water. According to differential scanning calorimetry data, the forward martensitic transformation (MT) took place in the range from À95°C to À85°C, and the reverse MT, from À 65°C to À 45°C after the RT.…”

“…It should also be noted that the hardness value of the studied alloy after RT is approximately 100 HV higher than that reported previously for equiatomic alloys. 24,25,28 This can be explained by the influence of various deformation mechanisms during the indentation process. 30 In the studied hyper-equiatomic Ti-Ni alloy at room temperature, the imprint is formed due to plastic deformation of B2-austenite.…”

“…4 , [11][12][13][14][15][16][17][18][19] To achieve the highest special (functional) properties, severe plastic deformation (SPD) can be applied based on methods such as equal-channel angular pressing, MaxStrain, abcpressing, and cold multipass rolling, since it can form an ultrafine-grained (UFG) structure. [20][21][22][23][24][25][26][27][28] The expansion of the application scope of these alloys as well as the complexity of their structure and intelligent devices based on SME and SE is accompanied by increased requirements on their properties. This leads to the necessity to optimize their manufacturing processes, which requires more detailed knowledges about the deformation and structure formation features of the material.…”

Evolution of Structure and Properties of Nickel-Enriched Ti-Ni Shape Memory Alloy subjected to Compressive Deformation

“…One of the most effective ways to control the FP is a thermomechanical treatment (TMT), which allows creating a wide spectrum of structures from a polygonized substructure to an ultrafine-grained structure [7][8][9]. The refinement of the structure is usually achieved by lowering of the deformation temperature and increasing of accumulated strain [9][10][11]. For obtaining of the ultrafine-grained structure in Ti-Ni alloys, various modes of severe plastic deformation are used: equal channel angular pressing [12,13], rotary forging [14], MaxStraindeformation [11,15] and high pressure torsion [16,17].…”

“…The refinement of the structure is usually achieved by lowering of the deformation temperature and increasing of accumulated strain [9][10][11]. For obtaining of the ultrafine-grained structure in Ti-Ni alloys, various modes of severe plastic deformation are used: equal channel angular pressing [12,13], rotary forging [14], MaxStraindeformation [11,15] and high pressure torsion [16,17]. The development of new TMT technologies for producing of Ni-rich Ti-Ni SMA which use lower deformation temperatures (below the recrystallization temperature) for effective structure refinement requires knowledge about the temperature ranges of hardening and softening processes during deformation in a wide temperature range.…”