Papers by Keyword: Invar Alloy

Abstract: This research aimed to prepare (Fe-Ni) alloy by powder technology method for its technological and commercial importance. Iron and Nickel powders were tacking then their powders mixed and blended together with percent (63% Fe-37% Ni), then the powders compacted isostatic cold pressure at (6 ton). Laser surface treatment was done for the samples with different energies (0, 200, 260, 300) mJ and pulse time (10 sec) At a distance (100 cm). The X-ray diffractions test indicated that all samples have Face Center Cubic (F.C.C), and the samples at 300 mJ has best properties which include increase of phases intensity and decrease of grain size according to Debye-Scherrer equation. The Atomic Force Microscope (AFM) also shows better properties with increase laser energy. Where increased soft-ness of surface, homogeneity surface and decrease in grain size with increase laser energy. The laser analysis resulted that melting all surface molecules which led to improvement in the structural properties.

Abstract: Thermodynamic equilibrium of Fe-36Ni-base Invar alloy containing C contents from 0.25 to 0.38 weight per cent during solidification has been investigated in this study. From the thermodynamic simulation using ThermoCalc®, it has been revealed that equilibrium phases which can be formed are two kinds of MC-type precipitates, i.e. (Nb, Mo, V)C and MoC, and M₂C carbides. The MoC carbide was expected to be formed at relatively lower temperature below 770^oC. Microstructure observation revealed the coarse precipitates in the as-cast ingots, which was Mo-rich non-equilibrium phase and could be resolved by the successive heat treatment. With increasing C contents from 0.25 to 0.38 wt.%, tensile strength of Invar alloy increased from 950 to 1100MPa after hot rolling and thermal expansion coefficient showed a trivial increase. Hot-rolled Invar alloy was successfully drawn at room temperature from 6 to 4 mm in diameter, which dramatically decreased thermal expansion coefficient.

Abstract: In this paper, the effect of different Ti content on the brazed joint microstructures was studied, including the reaction zone states, microstructures of the reaction interface on both ceramic and Invar alloy side. The added Ti content was 2%, 3%, 5%, 6% and 10%. The results showed that Ti had great effect on the thickness of reaction layer on the invar alloy side. Ti can inhibit the growth of the diffusion layer.

Abstract: Ni-Fe alloys ranging in composition of Fe rich invar (Ni100-xFeX, where x ~ 64), have a variety of high technology applications due to their wide spectrum of physical properties. In this paper, the effects of the applied potential (-1.20V, -1.35V) and the bath composition (0.1M, 0.01M) of the Ni-Fe alloy thin films are studied. Ni100-xFeX layers were electrodeposited onto Copper substrates with a pH of about 2.5. The experiments were performed at room temperature and the deposition time was equal to 10mn for all deposited samples. The experiments were performed using electrochemical techniques, by means of cyclic voltammetry (CV) and chronoamperometry (CA). The morphology and elemental composition of the deposited films were studied by means of electron microscopy coupled to EDS analysis.

Abstract: Strengthening method for the Fe-36Ni based Invar alloy for power transmission wire was investigated in this study. High strength of 1300 MPa could be obtained in this alloy through solution hardening, precipitation hardening and strain hardening by cold working. Phase equilibrium of the Invar alloy was calculated using FactSage®, revealing that thermodynamically stable phases are Mo2C, MoC, M23C6-type FeCrMo carbide, and M6C-type FeMo carbides. Aging treatments were carried out at temperatures ranging from 400 to 900oC for time intervals from 3 min to 30 hrs. Peak aging condition was obtained as 400oC and 1 hr. With temperature increased, peak hardness was decreased abruptly. Microstructure observation was conducted by optical microscopy, scanning electron microscopy, and transmission electron microscopy. By using the result from aging treatment, high strength above 1300MPa was obtained in the cold rolled Invar alloy plate.