The Role of Solidification Rate on Fiber Distribution and Mechanical Properties of a Directionally Solidified Nickel Base-Tac Eutectic

1981 ◽  
Vol 12 ◽  
Author(s):  
John L. Walter
Keyword(s):  
Base Alloy ◽  
Solidification Rate ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Strength ◽  
Directionally Solidified ◽  
Fiber Density ◽  
Alloy Matrix ◽  
Stress Rupture Life ◽  
Nickel Base

ABSTRACTA nickel base-TaC eutectic alloy consisting of 53 wt % Ni, 11 W, 3 Re, 5 Co, 3 Mo, 2 Al, 21.67 Ta and 1.33 C was directionally solidified at rates from 0.32 to 3.8 cm/hr. Samples were taken from the regions of aligned TaC fibers and tested in tension at 1000°C and in stress-rupture. The fiber density increased from 1×106 fibers/cm2 at 0.32 cm/hr to 27×106 fibers/cm2 at 3.8 cm/hr. The stress-rupture life at 927°C and 275.6 MPa ranged from 4 hrs for samples solidified at 0.32 cm/hr to 4187 hrs for the sample solidified at 2.54 cm/hr at which time the test was terminated. Examination, by transmission electron microscopy, of the samples tested at 1000°C in tension, to just the beginning of fiber breakage, revealed a change in the mode of deformation of the nickel-base alloy matrix with increasing fiber density. It was also seen that the TaC fibers deformed by two mechanisms; by slip and by the formation of stacking faults.It appears that tailoring the alloy composition to allow for higher solidification rates may be a more effective strengthener than alloying the matrix for high strength.

Influence of Heat Treatment on γ´ Phase and Property of a Directionally Solidified Superalloy

2018 ◽  
Vol 37 (3) ◽  
pp. 271-276
Author(s):  
P. C. Xia ◽  
K. Xie ◽  
H. Z. Cui ◽  
J. J. Yu
Keyword(s):  
Heat Treatment ◽  
Aging Temperature ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
Nickel Base Superalloy ◽  
Directionally Solidified ◽  
Stress Rupture Life ◽  
Stress Rupture Property ◽  
Nickel Base

AbstractThe effects of heat treatment process on microstructure and properties of a nickel base superalloy are investigated. The size of γ´ phase decreases and the stress rupture life of alloy at 1100 °C/60 MPa drops with the rise of cooling rate. The hardness at room temperature also increases. The size of cuboidal γ´ precipitate and the volume of spherical γ´ precipitate increase with the rise of aging temperature. With higher aging temperature, the alloy exhibits bimodal γ´ phase. A reasonable combination of the size and volume fraction of cuboidal and spherical γ´ phase can obtain better stress rupture property at 1100 °C/60 MPa.

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

High Temperature Rupture Life of Nickel-Based Superalloy under Directional Solidification with High Temperature Gradient

2017 ◽  
Vol 898 ◽  
pp. 422-429 ◽  
Author(s):  
Wei Guo Zhang ◽  
Zhi Jie Liu ◽  
Song Ke Feng ◽  
Fu Zeng Yang ◽  
Lin Liu
Keyword(s):  
High Temperature ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Temperature Stress ◽  
Solidification Rate ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Temperature Stress ◽  
Stress Rupture Life ◽  
Nickel Based Superalloy

The stress rupture life of DZ125 nickel-based superalloy that was prepared by directional solidification process under the temperature gradient of 500 K/cm has been studied at 900°C and 235MPa. The results showed that with the increase of directional solidification rate from 50 μm/s to 800 μm/s, the primary dendrite arm spacing reduced from 94 μm to 35.8 μm and γ' precipitates reduced and more uniformed in size. The high temperature stress rupture life of as-cast sample increased firstly and then decreased and reached its maximum at the solidification rate of 500 μm/s. The dislocation configuration of sample with refine dendritic structure after stress rupture was investigated and discovered that the dislocations in different parts of sample had different morphology and density, which indicated that the deformation of as-cast samples were uneven during high temperature stress rupture. A lot of dislocations intertwined around carbides and at the interface of γ/γ', and the dislocation networks were destroyed and the dislocations entered γ' precipitate by the way of cutting.

High-Temperature, Cobalt-Tungsten Alloys for Aerospace Applications

1965 ◽  
Vol 87 (1) ◽  
pp. 9-20 ◽  
Author(s):  
J. C. Freche ◽  
R. L. Ashbrook ◽  
G. D. Sandrock
Keyword(s):  
High Temperature ◽  
Rupture Strength ◽  
Rupture Life ◽  
High Stress ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Tungsten Alloys ◽  
Aerospace Applications ◽  
Temperature Capability ◽  
Nickel Base

The high-temperature capability and workability of cobalt-tungsten alloys for aerospace applications is discussed. The average life at 1850 F and 15,000 psi of the strongest previously reported alloy, Co-25 W-1Ti-1Zr-0.4C, was doubled from 92 to 185 hr by small additions of chromium and rhenium. At 2200 F and 5000 psi, the strongest alloy, Co-25W-1Ti-1Zr-3Cr-2Re-0.4C, had a rupture life of 23 hr; the elevated-temperature rupture strength compared favorably with the strongest available conventional (high-chromium) cobalt-base alloys. Above approximately 2035 F and at reasonably high stress levels (10,000 and 15,000 psi), its stress-rupture life also exceeded those of the strongest known nickel-base alloys, including the NASA tantalum-modified alloy and SM-200. It is particularly significant that even the strongest alloys of this series were readily hot-rolled. Ingots 1/2 in. thick were reduced to 0.065-in. sheet and subsequently cold-rolled to 0.0125-in. sheet. Elongations as high as 31 percent were obtained at room temperature with annealed sheet specimens. The good ductility obtained suggests that these alloys could be fabricated into complex shapes required for various aerospace and other applications. Although the strongest alloys had a chromium content of only 3 percent, they did not oxidize catastrophically in air.

NiCr-CrAl Coating for Ni3Al Base Alloy IC6AE

2007 ◽  
Vol 546-549 ◽  
pp. 1467-1470
Author(s):  
Shu Suo Li ◽  
Chun Xiao Zhang ◽  
Yong Wang Kang ◽  
Ya Fang Han
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Hot Corrosion ◽  
Base Alloy ◽  
Rupture Life ◽  
Stress Rupture ◽  
Tensile Tests ◽  
Stress Rupture Life ◽  
Obvious Effect ◽  
Resistance Tests

The effect of NiCr-CrAl coating on the microstructure, oxidation and corrosion resistance, as well as mechanical properties of Ni3Al base alloy IC6AE has been studied in the present investigation. NiCr-CrAl coating for alloy IC6AE was prepared by the powder pack cementation method. The oxidation resistance tests were carried out under the condition of 1050°C/100h, while the hot corrosion resistance tests were under 900°C/100h. The tensile tests at the room temperature and the stress rupture life tests under 1050°C/90Mpa have been also conducted. The experimental results showed that NiCr-CrAl as-coated specimens had excellent oxidation and hot corrosion resistance compared with the alloy IC6AE blank specimens, and NiCr-CrAl coating has no obvious effect on the mechanical properties of alloy IC6AE. It may be concluded that NiCr-CrAl coating is suitable for the alloy IC6AE.

Effects of Ru Additions on the Microstructures and Stress Rupture Life of a Directionally Solidified Ni-Based Cast Superalloy

2007 ◽  
Vol 546-549 ◽  
pp. 1201-1206 ◽  
Author(s):  
Xiao Lei Han ◽  
Ya Fang Han ◽  
Shu Suo Li ◽  
Wen You Ma
Keyword(s):  
Rupture Life ◽  
Stress Rupture ◽  
Aging Treatment ◽  
Incipient Melting ◽  
Directionally Solidified ◽  
Stress Rupture Life ◽  
Stress Rupture Properties ◽  
Heat Treated ◽  
Rupture Properties ◽  
Cast Superalloy

Two directionally solidified (DS) Ni-based cast superalloys without and with 3wt. % Ru were prepared. The effects of Ru addition on the microstructures and stress rupture properties of the heat treated superalloys were investigated. It is shown that the amount of eutectic in 3wt. % Ru alloy was less than that in alloy without Ru. The incipient melting structure was found after quenching followed by 1295°C and 1300°C solid solution treatments in 3wt. % Ru alloy and in the alloy without Ru, respectively. The temperature at which the eutectic pools dissolved completely was higher than the temperature at which incipient melting appears. In order to obtain the better mechanical properties, double aging treatment was carried out for both alloys to optimize the sizes, morphologies and distribution of the γ′ phase. The stress rupture lives of the alloys were 55h and 108h under the condition of 1070°C and 137MPa the alloys without Ru and with 3wt. % Ru respectively. It is suggested that 3wt. % Ru addition can prolong the stress rupture life of the alloy.

Effects of Long-Term Aging at 1070°C on Microstructure and Mechanical Properties of Ni3Al-Base Alloy IC6E

2010 ◽  
Vol 650 ◽  
pp. 205-209 ◽  
Author(s):  
Ming Li ◽  
Jin Xia Song ◽  
Shu Suo Li ◽  
Ya Fang Han
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Base Alloy ◽  
Rupture Life ◽  
Stress Rupture ◽  
Stress Rupture Life ◽  
Microstructure And Mechanical Properties ◽  
Stress Rupture Properties ◽  
Essential Change

The effect of long-term aging at 1070°C on microstructure and mechanical properties of Ni3Al-base equiaxed superalloy IC6E was investigated. The microstructure change during aging for periods of 100 to 1500h was examined by SEM . Results showed that alloy IC6E underwent following microstructure changes during aging: γ' phases coalesced and grew, γ phases became disconnected and coarsened, the content of Mo (the solution-hardening element of γ and γ' phases) in γ' phases decreased, Y-NiMo phases precipitated from γ phases both at grain boundaries and within grains, and γ' bands and large γ phases emerged along grain boundaries. The tensile and stress rupture properties after aging were determined. The results showed that the yield strength of alloy IC6E at room temperature decreased obviously after aging for 100 h, and reduced slowly during further aging. The stress rupture life under 1070°C, 80MPa also had no essential change during aging.

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