Martensitic transformation and shape memory effect in ausaged Fe–Ni–Si–Co alloys

Microstructure, hyperfine interaction and magnetic transition of Fe-25%Ni-5%Si-x%Co alloys

“…Tanaka et al investigated the effect of Co addition on the microstructure, shape memory effect and mechanical properties in Fe-28Ni-6Si and Fe-28Ni-6Si-10Co alloys and reported that both were composed of lenticular martensite in non ausaged alloys [5]. In our study however, we could observe no lenticular martensite in the Fe-%24.5Ni-%4.5Si alloy which may be attributed to the amount of Ni used in our previous study [12].…”

“…From this result, we can say that addition of Co to Fe-%25Ni-%5Si alloy causes the formation of lenticular martensite. It is well accepted that the martensite morphology is dependent on many factors, such as alloy composition [4,5,7], austenite grain size [19], ausaging [2,20], and martensite formation temperature [7,16], however no one has shed light on the reason why morphology exists in ferrous α martensite so far.…”

“…It is also well known that the plastic deformation of austenite can induce martensitic transformation in Fe based alloys and martensitic transformation can be also induced under different external forces such as hydrostatic pressure and magnetic field [1][2][3]. The elements constituting the alloy is one of the important factors affecting the characteristics of martensitic transformation such as hardness of austenite, morphology of martensite, effect of shape memory and magnetic properties of alloys Hyperfine Interact (2016) 237:11 [4][5][6][7]. For instance, even a small amount of Si, Mo or Co addition changes the martensite morphology, magnetic properties and hardness of the alloy [4,6,8,9].…”

On the effect of gamma phase formation on the pseudoelastic performance of polycrystalline Fe–Mn–Al–Ni shape memory alloys

“…Iron based shape memory alloys (SMAs) such as Fe-Ni-Co- 39 based and Fe-Mn-based alloys have attracted considerable 40 attention in recent years [1][2][3][4][5][6][7][8][9][10][11][12]. Following the development of 41 Fe-Ni-Co-Ti SMAs, which are characterized by relatively low 42 reversible transformation strains [7][8][9][10], Fe-Ni-Co-Al-based alloys 43 were introduced showing almost perfect pseudoelastic strains up 44 to 13% in the polycrystalline state, as shown for Fe-Ni-Co-Al-Ta 45 by Tanaka, Kainuma and co-workers [11]. More recently, Omori 46 et al [13] Fe-Mn-Al-Ni SMA became a candidate material for use in 55 aerospace, automobile and seismic applications.…”

Shape memory in ferrous alloys

“…However, the addition of about 10% Co to this alloy resulted in a marked improvement in shape memory. In the case of aged Fe-28%ni-10%Co-6%Si alloy, increased shape memory is associated with a rise in the Curie temperature, a decrease in the transformation temperature, the formation of thin-plate martensite, a decrease in the volume change, intensification of g¢ precipitation and an increase in the hardness of the austenite (Tanaka et al, 2006). nevertheless, the transformation hysteresis remains high, the martensite tetragonality increases only marginally (from 1.00 to 1.01) and the strain recovery is only about 50% of 2% bending strain.…”