THE TERM SHAPE MEMORY ALLOYS (SMA) is applied to that group of metallic materials that demonstrate the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Generally, these materials can be plastically deformed at some relatively low temperature, and upon exposure to some higher temperature will return to their shape prior to the deform...

Twinned growth behaviour in the rapidly emerging area of two-dimensional nanomaterials still remains unexplored although it could be exploited to fabricate heterostructure and superlattice materials. Here we demonstrate how one can utilize the twinned growth relationship between two two-dimensional materials to construct vertically stacked heterostructures. As a demonstration, we achieve 100% o...

The experimental facts on the stabilisation of martensite in copper base shape memory alloys, of interest to the scientific investigator and the practical alloy processor and user are reported. Factors that have an influence on stabilisation are considered in this respect. The mechanisms proposed in the literature to explain stabilisation are critically examined.

Austenitic carbon steels that exhibit excellent mechanical properties due to the twinning-induced plasticity effect have been studied extensively. On the other hand, austenitic stainless steels usually achieve good strength and ductility via transformation-induced plasticity. However, relying on martensite transformation for strength may cause problems such as delayed cracking. Therefore, the t...

The fct martensite morphology and the martensite transformation temperatures are examined for Pd-rich Fe–Pd–Pt alloys, which have the composition of Fe–(xPdyPt)xþy1⁄430 at:%. The replacement of Pd with Pt content causes solution hardening. The shape memory effects are investigated below the Af temperatures. Above the Af temperatures, the stress induced martensite in several grains completely di...

The two-way shape memory effect in a Ti36Ni49Hf15 high temperature shape memory alloy (SMA) has been systematically studied by bending tests. In the TiNiHf alloy, the martensite deformation is an effective method to get two-way shape memory effect even with a small deformation strain. When the TiNiHf alloy is deformed at a full martensite state, the deformation mechanism is the martensite orien...

Pseudoelasticity and the shape memory e ect (SME) due to martensitic transformation and reorientation of polycrystalline shape memory alloy (SMA) materials are modelled using a free energy function and a dissipation potential. Three di erent cases are considered, based on the number of internal state variables in the free energy: (1) Austenite plus a variable number of martensite variants; (2) ...

Austenitic high manganese steels exhibit outstanding mechanical properties, such as energy absorption, owing to various deformation-mechanisms dislocation slip, twinning-induced plasticity (TWIP) and transformation-induced (TRIP). Here, we show a novel thermomechanical treatment manufacture steel Fe–18Mn-0.3C (wt.-%) with excellent performance by combining these three deformation-mechanisms. Th...

Utilizing electrical resistance measurements in combination with strain observations on single crystals, it was possible to distinguish the austenite to martensite transformation from the detwinning of the martensite behavior during deformation of NiTiCu shape memory alloys. It was found that the electrical resistance change associated with the detwinning of the martensite variants was as high ...

In the current paper, a predefined thermomechanical procedure has been applied to two-way shape memory effect (TWSME) in NiTi alloy study of two different load conditions on induced martensitic state. The microstructure strips was studied using optical microscopy (OM), scanning electron (SEM) fitted with an EDS microprobe, and microhardness tests at end both training thermal cycles. Inducing in...