Experimental study of spring back of different sheet alloys by pre-load laser bending

In this paper, effect on spring back values of different materials before and after laser bending are studied. Four different alloys were selected for laser bending test: Aluminum Alloy Al-5052M, Stainless Steel Alloy-304M, Low Carbon Steel (perpendicular rolling direction) and Titanium Alloy Ti-6Al-4V (TCL4). Thickness of alloys sheet is almost same. The influence of different mechanical parameters like tensile strength and hardness on spring back values before and after pre-loaded laser bending were analyzed. The results were compared which showed that Al-alloys has large amount of spring back even at small amount of displacement before laser bending which is due to their low tensile strength. But after laser bending titanium alloys have high value of spring back as compare to before pre-loaded laser bending value proving that this laser bending technique can be a useful method for those alloys which are not easy to deform at normal temperature

In vitro corrosion behavior and cytocompatibility of pure Fe implanted with Ta

In this study, pure Fe was surface-modified by Ta ion implantation with different incident ion doses. Its surface morphology and chemical composition were investigated using atomic force microscopy and auger electron spectroscopy. Results showed that Ta ion implantation led to the formation of Ta/Fe oxide mixtures at the outmost surface (60–80 nm in thickness) of the implanted layer. Results from electrochemical measurements and immersion tests indicated that the corrosion rate of the pure Fe in simulated body fluids can be accelerated after the Ta ion implantation. The in vitro cell culture results showed that the cytocompatibility of osteoblasts on the pure Fe has been significantly improved by applying the Ta ion implantation

Observation of the Anomalous Hall Effect in a Collinear Antiferromagnet

Time-reversal symmetry breaking is the basic physics concept underpinning many magnetic topological phenomena such as the anomalous Hall effect (AHE) and its quantized variant. The AHE has been primarily accompanied by a ferromagnetic dipole moment, which hinders the topological quantum states and limits data density in memory devices, or by a delicate noncollinear magnetic order with strong spin decoherence, both limiting their applicability. A potential breakthrough is the recent theoretical prediction of the AHE arising from collinear antiferromagnetism in an anisotropic crystal environment. This new mechanism does not require magnetic dipolar or noncollinear fields. However, it has not been experimentally observed to date. Here we demonstrate this unconventional mechanism by measuring the AHE in an epilayer of a rutile collinear antiferromagnet RuO$_2$. The observed anomalous Hall conductivity is large, exceeding 300 S/cm, and is in agreement with the Berry phase topological transport contribution. Our results open a new unexplored chapter of time-reversal symmetry breaking phenomena in the abundant class of collinear antiferromagnetic materials.Comment: 33 pages, 14 figures, 2 table

Heusler type CoNiGa alloys with high martensitic transformation temperature

A strong need exists to develop new kinds of high-temperature shape-memory alloys. In this study, two series of CoNiGa alloys with different compositions have been studied to investigate their potentials as high-temperature shape-memory alloys, with regard to their microstructure, crystal structure, and martensitic transformation behavior. Optical observations and X-ray diffractions confirmed that single martensite phase was present for low cobalt samples, and dual phases containing martensite and gamma phase were present for high cobalt samples. It was also found that CoNiGa alloys in this study exhibit austenitic transformation temperatures higher than 340 degrees C, showing their great potentials for developing as high-temperature shape-memory alloys

van der Waals Magnets: Material Family, Detection and Modulation of Magnetism, and Perspective in Spintronics

Abstract van der Waals (vdW) materials exhibit great potential in spintronics, arising from their excellent spin transportation, large spin–orbit coupling, and high‐quality interfaces. The recent discovery of intrinsic vdW antiferromagnets and ferromagnets has laid the foundation for the construction of all‐vdW spintronic devices, and enables the study of low‐dimensional magnetism, which is of both technical and scientific significance. In this review, several representative families of vdW magnets are introduced, followed by a comprehensive summary of the methods utilized in reading out the magnetic states of vdW magnets. Thereafter, it is shown that various electrical, mechanical, and chemical approaches are employed to modulate the magnetism of vdW magnets. Finally, the perspective of vdW magnets in spintronics is discussed and an outlook of future development direction in this field is also proposed

Determination of bulk domain structure and magnetization processes in bcc ferromagnetic alloys: Analysis of magnetostriction in Fe83Ga17

The ground state of macroscopic samples of magnetically ordered materials is a domain state because of magnetostatic energy or entropy, yet we have limited experimental means for imaging the bulk domain structure and the magnetization process directly. The common methods available reveal the domains at the surface or in electron- or x-ray transparent lamellae, not those in the bulk. The magnetization curve just reflects the vector sum of the moments of all the domains in the sample, but magnetostriction curves are more informative. They are strongly influenced by the domain structure in the unmagnetized state and its evolution during the magnetization process in an applied field. Here we report a method of determining the bulk domain structure in a cubic magnetostrictive material by combining magneto-optic Kerr microscopy with magnetostriction and magnetization measurements on single crystals as a function of applied field. We analyze the magnetostriction of Fe83Ga17 crystals in terms of a domain structure that is greatly influenced by sample shape and heat treatment. Saturation magnetostriction measurements are used to determine the fraction of domains orientated along the three ?100? axes in the initial state. Domain wall motion and rotation process have characteristic signatures in the magnetostriction curves, including those associated with the ?E effect and domain rotation through a ?110? auxetic direction