Effects of electropulsing treatment on mechanical properties in Ti rich TiNi shape memory alloy

Abstract

The influence of electropulsing treatment on thermomechanical behaviour in terms of transformation temperatures and mechanical properties of a cold worked Ti rich TiNi shape memory alloy was studied. The results showed that the transformation temperatures increase with increasing current intensity. The superelasticity of the alloy is improved after the electropulsing treatment, and the hardness of the alloy decreased with increasing current intensity. The microstructure of the alloy showed that the above changes can be attributed to the decreasing dislocation density due to the current pulses.

Application of High-Density Electropulsing to Improve the Performance of Metallic Materials: Mechanisms, Microstructure and Properties

“…As early as the 1990s, scientists and engineers have studied the effect of electric current pulse on the structures and properties of metallic materials by investigating ‘electromigration’ [ 2 , 3 ] and the ‘electro-plasticity effect’ [ 4 ] in metals. Subsequently, electric current pulses were applied to a variety of metals and alloys, including copper [ 5 , 6 , 7 , 8 , 9 , 10 ], titanium [ 11 , 12 ], magnesium alloys [ 13 , 14 , 15 , 16 ], aluminium alloys [ 17 , 18 ], tungsten [ 19 ], steels [ 20 , 21 , 22 , 23 , 24 ], shape memory alloys [ 25 , 26 , 27 , 28 , 29 ], amorphous crystals and metallic glass [ 30 , 31 , 32 , 33 , 34 ]. The influence of electropulsing on the properties and performance of metallic materials depends on their original microstructure, crystal orientation, crystallinity and the degree of deformation.…”

Electropulsing-induced plastic deformation in an interstitial free steel

“…Literature reports a wide range of EP-induced micro structure-property changes. These range from plastic deformation [5,[11][12][13][14]21] to recovery-recrystallisation [2,5,6,15,16,20,[34][35][36][37] and even dynamic recrystallisa tion [8,18], from phase transformation [3,9,[38][39][40] to the dissolution of the second phase [4] and crystallisation [41][42][43][44][45], from grain refinement [1,19] to possible modifications in slip systems [17] and developments of preferred orientations [1,46], from crack healing [7,[47][48][49] to improvements in machinability [50,51] -the list is indeed exhaustive. Researchers tried to explain the EP-induced changes from the tenets of electromigration theory [5] and/or multiple other factors [1,5].…”

“…The electroplastic effects, on the other hand, are attributed [5][6][7][8] to possible interactions between drifting conduction electrons and dislocations. Despite a large reservoir of excellent literature [1][2][3][4][5][10][11][12][13][14][15][16][17][18][19][20][21] on the subject, often such available published documents are phenomenological, lack in direct experimental observations and provide incomplete analysis for the mechanisms behind EP-induced microstructural changes. These formulated the motivation behind the present study.…”

The Electrical Processing of Materials

“…[4][5][6] If the temperature rise associated with the pulsing is sufficient, then the dislocation density can be affected even if the pulse duration is just a few millionths of a second. 7 In a recent editorial, I commented on the promise of the method, which thus far has not had any major exploitation, and on the need for a theoretical framework that is quantitatively predictive. 8 To explore these ideas further, a critical assessment was commissioned, 9 the conclusions from which can be paraphrased as follows:…”