To expand our knowledge of the martensitic transformation from a B2 to an L10 structure for ferromagnetic shape memory Co-Ni-Al alloys, we have performed first-principles band calculations for the supercell structures corresponding to Co1 xNi1þxAl (x 1⁄4 0, 1=2) in a nonmagnetic state. From the investigation of total energy vs c=a, we have found that the total-energy gain for x 1⁄4 0 due to the...

Dissimilar metals friction welding of austenitic–martensitic stainless steels is commonly used in order to manufacture engine valves in the automobile industry. In this study, X53CrMnNiN219 (austenitic stainless steel) and X45CrSi93 (martensitic stainless steel) valve steel rods were welded by friction welding process. The welded joint was then heat treated at 760 0C for 60 min. Mechanical prop...

Some of the most interesting, and technologically important solid–solid transformations are the 1rst order di2usionless transformations that occur in certain equiatomic, ordered, bi-atomic crystals. These displacive transformations include thermally-induced, reversible, proper martensitic transformations as seen in shape memory alloys such as NiTi (where group–subgroup relationships exist betwe...

The previous work of Professor W. G. Burgers and Dr. A. J. Bogers is used to develop a mechanism of strain-induced martensitic nucleation, involving two intersecting shear systems. We distinguish between strain-induced nucleation and stressassisted nucleation, the latter involving the same sites and embryos as does the regular spontaneous transformation. The strain-induced nucleation, on the ot...

Abstract. We investigate the statistics of the transformation-strains that arise in random martensitic polycrystals as boundary conditions cause its component crystallites to undergo martensitic phase transitions. In our one-dimensional polycrystal model the orientation of the n grains is given by an uncorrelated random array of the orientation angles θi, i = 1, . . . , n. Under imposed boundar...

The martensitic transformation and magnetic properties of ferromagnetic shape memory alloy Ni50+ xFe25− xGa25 (x = −1, 0, 1, 2, 3, 4) ribbons have been systematically studied. It has been found that with the increase of Ni concentration, the martensitic transformation temperature increases, but the Curie temperature decreases. Both the two-step thermally induced structural transformation and th...

Metallographic, X-ray diffraction and magnetometric analysis were used to study the regularities of martensitic transformation in melt-spun ribbons of a Fe - 28 wt. % Ni - 2.1 wt. % Ti - 2 wt. % Al - 0.05 wt. % C alloy. The substantial differences in volume fractions of the martensite phase in local regions of thin melt-spun ribbons of the alloy are related to the size effect of the transformat...

We study the reconstructive martensitic transformations in crystalline solids (i.e., martensitic transformations in which the parent and product lattices have arithmetic symmetry groups admitting no finite supergroup), the best known example of which is the bcc–fcc transformation in iron. We first describe the maximal Ericksen-Pitteri neighborhoods in the space of lattice metrics, thereby obtai...

Grain structure control is challenging for metal additive manufacturing (AM). Grain structure optimization requires the control of grain morphology with grain size refinement, which can improve the mechanical properties of additive manufactured components. This work summarizes methods to promote fine equiaxed grains in both the additive manufacturing process and subsequent heat treatment. Influ...