[en] Tensile properties and deformation mechanisms of Nimonic 105 superalloy were investigated at temperatures from room temperature (RT) to 1000 °C. The results showed that serrations were present in the stress-strain curves of the alloy at temperatures of 300–600 °C, and the nature of serrations changed from type A to type (A + B) and then to type C with increasing temperature. The ultimate tensile strength of the alloy decreased gradually from RT to 700 °C and then decreased remarkably with increasing further temperature. The yield strength of the alloy did not significantly change from RT to 750 °C, while it droped rapidly above 800 °C. Transmission electron microscopy (TEM) observations revealed that the main deformation mechanism of alloy below 750 °C was strongly-coupled dislocation pairs shearing, whereas Orowan looping and climb and cross-slip of dislocations acted as the principal deformation mechanisms above 800 °C. Moreover, a few deformation twins and extended stacking faults were observed in the matrix at temperatures of 750–800 °C. On the basis of experimental results, the relationship between tensile properties of the alloy and deformation mechanism was discussed.

[en] Single crystals of the commercial nickel-base superalloy NIMONIC 105 with four different orientations have been compression tested in the temperature range 600-1150 K. NIMONIC 105 is strengthened by fine, coherent, shearable, homogeneously distributed precipitates of the L1₂-long-range ordered γ'-phase (47 vol.%). The same investigations were undertaken for single crystals of the two constituent phases: L1₂-ordered, intermetallic single-phase γ' and disordered single-phase f.c.c. γ-matrix. Their compositions were those of the two equilibrium phases of NIMONIC 105. The CRSS of NIMONIC 105 and of the γ'-phase were anisotropic in the whole temperature range. The CRSS of the γ-matrix was isotropic. The interpretation of the anisotropy of NIMONIC 105 follows that of single-phase L1₂-ordered γ'. (orig.)

[en] γ'-precipitates have been grown in the nickel-base superalloy NIMONIC 105 by an Oswald ripening treatment. After that their and the γ-matrix' compositions have been determined by energy dispersive X-ray analyses. Strong concentration gradients were found next to the γ-γ'-phase-boundary. Their major part was within the γ'-particles, whose outer layers were relatively rich in Co and Cr and too poor in Ni and Al. The concentration gradients observed within the γ'-particles are interpreted on the basis of the diffusion processes controlling their growth. (orig.)

[en] In this study, the formation and transformation of σ and M₂₃C₆ phases in Nimonic 105 superalloy at different level of boron were investigated. So alloys with two levels of boron were prepared and the microstructure were analyzed using optical and scanning electron microscopy and X-ray diffraction. It was found that the time of M₂₃C₆ formation, M₂₃C₆ transformation into σ phase and grain growth mechanism were influenced by boron addition. Boron segregated at the grain boundaries and changed the morphology of M₂₃C₆ from continuous to discontinuous one. M₂₃C₆ transformed to needle-like σ precipitates at 750 °C after 360 and 240 h heating and the σ volume fraction reached to 2.2 and 3.4 vol% after 500 h in the alloys containing 0.013 and 0.003 wt% B, respectively. Furthermore, the time-temperature- precipitation (TTP) diagrams of M₂₃C₆ phase were presented. It was observed that time and temperature formation of M₂₃C₆ precipitation shifted to higher times and temperatures as a result of boron addition. (paper)

[en] The age hardening behavior and microstructural characteristics of a 53Ni-20Co-15Cr-5Mo-4.9Al-1.3Ti alloy has been investigated by micro-Vickers hardness test and transmission electron microscopy. The shape of γ' precipitates was spherical at the early stage of aging and was cuboidal at the later stage. The aged hardness of the alloy closely related to the size and the quantity of γ' precipitates. The γ' precipitation cannot be suppressed by water quenching after solution treatment. It is necessary to cool the specimen at rates of higher than 10⁴ K/s for restraining the precipitation of γ' phase. The growth kinetics of γ' precipitates in the alloy followed the prediction of Lifshitz-Slyozov-Wagner (LSW) theory for growth under volume diffusion control at all aging temperatures examined. The activation energy for the growth was estimated to be 266 kJ/mol which was close to those of diffusion of solute atoms such as Al, Ti and so on in Ni and Ni-base alloys. The actual particle size distribution of γ' precipitates was somewhat different from distributions predicted by the LSW and Brailsford-Wynblatt encounter modified (BWEM) theories. (author)

[en] A novel Ni-based superalloy was designed with γ precipitate strengthening, controlled γ/γ lattice misfit and high configurational entropy of the γ matrix for improved high temperature performance up to 800 °C. The alloy contains nano-sized γ precipitates, MC and other grain boundary carbides. Three variants of the alloy were fabricated using vacuum induction melting, a computational-based homogenization cycle for reducing solidification segregation, and thermomechanical processing steps of forging followed by hot rolling to produce plates from which ASTM standard test specimens were extracted. Tensile testing at room temperature and elevated temperatures up to 800 °C revealed superior yield stress when compared to Nimonic 105 with good tensile strength values. Furthermore, the three alloys are machinable with maximum stresses comparable to standard practices as determined using deformation mechanisms maps obtained from Gleeble testing and EBSD analysis. Due to the composition of the experimental alloys falling outside the typical range used to populate thermodynamic databases, differences in phase predictions and related temperatures were observed between the experiment and Thermo-Calc predictions. The γ forming elements Ti and Nb had a similar effect on the γ precipitates and indirectly contributed to changing the entropy of the γ matrix. Based on the results of this study, these alloys have the potential for use at 800 °C in energy structural applications. Definitions related to this novel class of alloys are discussed.

[en] In the present study, the effects of boron and zirconium on the microstructure and high-temperature tensile properties of Nimonic 105 superalloy were evaluated. For this purpose, three alloys with different contents of boron and zirconium (0.003 wt% B-0 wt% Zr, 0.013 wt% B-0 wt% Zr, 0.003 wt% B- 0.16%wt% Zr) were prepared via VIM + ESR process. Optical and scanning electron microscopes, x-ray diffraction analysis and tensile testing at 25 and 700 °C were used to describe the alloys structure and properties. The results showed that the microstructure of the 0.003 wt% B-0 wt% Zr alloy consisted of thin-film (Cr, Mo)₂₃C₆ and blocky (Ti, Mo)C phases in the γ matrix. The addition of zirconium changed the type of carbide to MC one while boron improved the formation of discrete M₂₃C₆-type carbide. The XRD analysis results revealed an increase in the lattice misfit of the γ/γ´ phase for the B and Zr-added alloy, a decrease in the M₂₃C₆/γ misfit for the B-added alloy and the MC/γ phase misfit for the Zr-added alloy. In addition, a significant effect of zirconium on grain size were observed in the alloys. Boron and zirconium decreased the ductility at room temperature by 3% and 6% and increased it at 700 °C by 7% and 13%, respectively. Moreover, boron and zirconium increased the high-temperature yield strength by 9% and 13% and ultimate tensile strength by 9% and 16%, respectively. (paper)

[en] Above T_max∼1050 K, the yield strength σ_t of the commercial γ'-strengthened nickel-base superalloys NIMONIC PE16, NIMONIC 105, and of many similar superalloys decreases drastically. In order to elucidate the physical reasons for this softening effect, σ_t has been measured as a function of the deformation temperature and of the plastic strain rate. Moreover, the configurations of dislocations in deformed specimens have been studied by transmission electron microscopy (TEM). The results are as follows: in NIMONIC 105, the relevant dislocation processes change at T_max: below T_max pairs of dislocations with Burgers vectors of the type (1/2)<1 1 0> shear the strengthening γ'-precipitates athermally whereas above T_max single (1/2)<1 1 0>-dislocations overcome them thermally activated. The effects of changes of the γ'-precipitate dispersion with temperature are negligible. In NIMONIC PE16, however, both mechanisms--changes of the γ'-dispersion and thermally activated dislocation processes--strongly affect σ_t above T_max

[en] Automatic translation: 1. Summary: The material tests carried out at BBC-D in phase I of the HHT project included - Determination of the influence of reactor-specific contaminated helium on the creep behavior various high temperature alloys (work area VII, project 1.l) and - Development and testing of a turbine blade made of Ti-Zr-alloyed molybdenum in the powder metallurgical variant (P / M-TZM) (work area VII Projects 2.1, 2.2 and 2.3) Creep tests were carried out on the two investment casting alloys Inconel 713 LC and MM 004, on the forging materials Nimonic 80 A and Nimonic 105 as well as Ti-Zr alloy Molybdenum (TZM) in an arc-melted state 500, 650 and 850 ° C for a maximum of 16,000 h in air, reactor-specific contaminated helium and pure helium. No differences could be found in the test period observed in the creep behavior due to environmental influences become.

[en] In engines valves are essential components for better working of engine. The Intake and exhaust valves are used to control the flow and exchange of gases. These valves seal the working space inside the cylinder against the manifolds and are opened and closed with the valve train mechanism Smooth-running of internal combustion engine is possible because of exhaust valve. Role of the exhaust valve is to pass on the exhaust gases to the exhaust manifold from the combustion chamber. During the operation of internal combustion engine, exhaust valves are subjected to the axial stresses due to exhaust gas pressure, cyclic stresses due to return spring load, thermal stresses due to very high temperature inside the combustion chamber and inertia force arising on the account of valve assembly. This project aims to Design and static -thermal analysis on poppet valve applications of CI engine. Modeling of the valve was done in the Catia and static-thermal analysis was carried out in the ANSYS. In thermal analysis determined, total heat flux and temperature. Here used five materials are Stainless steel, Nimonic 80A, Nimonic 105, Aluminum nitride, Silicon Nitride finally suggested best material for poppet valve on these materials. (paper)