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[en] New methods of corrosion monitoring are being developed for tanks containing high-level radioactive waste. The prototype corrosion and chemical analysis probe, which is under production, provides for monitoring vertically in the tank with an adjustable probe head. The probe monitors corrosion using electrochemical noise and chemistry with Raman spectroscopy. Electrochemical noise involves the monitoring of potential and current signals from two sets of electrodes. The electrodes are constructed of carbon steels similar to those for the tank wall and internal cooling coils. The system design and initial laboratory testing are discussed
[en] Tensile behavior of a new single-crystal nickel-based superalloy with rhenium (CMSX-4) was studied at both room and elevated temperatures. The investigation also examined the influence of γ' precipitates (size and distribution) on the tensile behavior of the material. Tensile specimens were prepared from single-crystal CMSX-4 in  orientation. The test specimens had the  growth direction parallel to the loading axis in tension. These specimens were given three different heat treatments to produce three different γ' precipitate sizes and distributions. Tensile testing was carried out at both room and elevated temperatures. The results of the present investigation indicate that yield strength and ultimate tensile strength of this material initially increases with temperature, reaches a peak at around 800 C, and then starts rapidly decreasing with rise in temperature. Both yield and tensile strength increased with increase in average γ' precipitate size. Yield strength and temperature correlated very well by an Arrhenius type of relationship. Rate-controlling process for yielding at very high temperature (T ≥ 800 C) was found to be the dislocation climb for all three differently heat-treated materials. Thermally activated hardening occurs below 800 C whereas above 800 C thermally activated softening occurs in this material
[en] Studies were conducted on the relationship between the composition of Nd-Fe-B alloys, the temperature of the substrate, additional heat treatment and magnetic properties, crystalline phases, and microstructure and texture of films 30 to 300 μm thick produced by ion-plasma sputtering of cast targets. The sputtering rate was maintained at ∼30 μm/h. The axial crystalline texture (001) along the normal to the sputtering plane is formed at a sputtering temperature within the limits ranging from 300 to 450 C and higher than 600 C. In the intermediate domain of sputtering temperatures, there is a deterioration of the texture (001), or such a change of the indices of the texture when the normal to one of the planes of the zone  becomes its axis. Within the framework of the classical theory of crystallization, a model of growth texture formation during the course of sputtering is suggested. The model explains the nonmonotonic change of texture with the change of sputtering temperature. The data obtained about the structure and properties of films have made it possible to optimize the sputtering process with a view to obtaining sputtered magnets with very good permanent magnet properties. Examples of magnetic systems and devices with sputtered magnets are given
[en] The present investigation was carried out to assess the localized corrosion resistance of materials proposed for the construction of the safety-grade sodium-to-air decay-heat removal system for fast breeder reactors. The materials, such as Alloy 800, 9Cr-1 Mo steel, and type 316LN stainless steel, in different microstructural conditions were assessed for pitting and stress-corrosion cracking resistances in a chloride medium. The results indicated that 9Cr-1Mo steel in the normalized and tempered condition can be considered for the above application from the standpoint of corrosion resistance
[en] A comparative study was made of structure and magnetic properties of Nd8Fe88B4 prepared by mechanical alloying (MA) using elemental powders as starting materials and by mechanical milling (MM) of the alloy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) combined with transmission electron microscopic (TEM) studies revealed that both milling procedures resulted in a mixture of α-Fe and an amorphous phase. The thermal stability of the as-milled powders produced by MA was comparable to that of the as-milled powders produced by MM. Heat treatment of the milled powders above the crystallization temperature resulted in the formation of a nanocrystalline mixture of Nd2Fe14B and α-Fe, but annealed MA powders demonstrated a somewhat coarser structure in comparison with annealed MM powders. Therefore, higher remanences and coercivities were obtained by MM
[en] Directional solidification was used to produce turbine blades by the Bridgman method. NITAC alloys with various carbon contents were investigated; the optimum range was found to be 0.40 to 0.48%. Within this range, except for the blade locking piece edges, the blade structure consisted predominantly of aligned eutectics. The in-situ eutectics were aligned tantalum fibers embedded in a γ-phase matrix. The blades were produced using an alloy displacement rate of 1.86 x 10-6 m/s. Measurements of fiber spacings along the blade height indicated that the rate of displacement of the solidification front exhibited some variations. These variations were closely associated with dimensional changes in the turbine blade cross sections
[en] By adding various amounts of CeB6, high-speed steel (M3:2) was consolidated by powder metallurgy in the form of sintering. The addition of CeB6 improved the density of the sintered steel and the formation of M6C phase in microstructure. It is speculated that CeB6 was decomposed into boron and cerium. Boron atoms were enriched in M6C carbide phases, but cerium atoms were mainly clustered on grain boundary while they were converted to oxides, whereby the mechanical properties were improved. For example, upon the sintering at 1210 °C, relative density ~ 98.5% and average grain size ~ 18 μm were obtained with CeB6 content at 0.3 wt.%. Excellent mechanical properties, e.g., the Rockwell hardness ~ 52 HRC, flexural strength ~ 3.05 GPa, and fracture toughness ~ 40.92 MPa m1/2, were achieved in the sample containing 0.3 wt.% CeB6, which implies accordingly remarkable increases by 23.5, 38.1, and 23.7%, of the properties compared with those in the sample free of CeB6.
[en] Microstructural and mechanical properties of 2.0-mm-thick 2060 Al-Cu-Li alloy joints obtained at different rotation speeds were assessed in this study. The rotation speeds ranged from 400 to 1300 rpm, with welding speed kept at a constant value of 100 mm/min. With the increase in rotation speed, grain coarsening occurred while the density of precipitation decreased in the stir zone (SZ), and great amounts of the Al2CuLi and Al2Cu phases were dissolved while only small amounts of the Al3Zr and Al3Li phases remained. The lowest hardness was found at the interface between the heat-affected zone (HAZ) and thermo-mechanically affected zone (TMAZ); the average hardness value of SZ increased, while the lowest hardness moved in the direction away from the center of joints. The ultimate strength (UTS) of weld first increased rapidly and then slowly decreased as rotation speed increased, with a maximum value of 443 MPa obtained at a rotation speed of 600 rpm, reaching 83.58% of the base metal (BM) strength. Three fracture modes were established to illustrate the growth mechanism of the crack. Analysis of the fracture surface showed that insufficient materials flowed and coarsened secondary phases caused the joint fracture.
[en] Microstructure and mechanical properties after induction hardening have a significant effect on the wear resistance performance and lifetime of 55CrMo steel ball screw. In the paper, the dilatometric curves were recorded at the different heating rate by a Gleeble-1500D thermo-mechanical simulator to determine the effect of heating rate on the austenitizing temperature of 55CrMo steel. Heat treatment of some specimens was performed by the Gleeble-1500D thermal simulator at the different heating temperature, holding time and cooling rate to investigate the effect of induction hardening parameters on the phase transformation, microstructure and microhardness of 55CrMo steel. Microstructure of specimen was analyzed using an optical microscope and a scanning electron microscope. Volume fraction of retained austenite was measured using an x-ray diffractometer. The mechanical properties were evaluated by a microhardness tester. The results show that the austenitizing temperature of 55CrMo steel increases with the increasing heating rate. Increasing the heating temperature, holding time and cooling rate of specimen is helpful in obtaining a uniform cryptocrystalline martensite. Volume fraction of retained austenite is less as the heating temperature is in the range of 900-950 °C. In the induction hardening of 55CrMo steel, the heating temperature should be in the range of 900-1000 °C.