Special Features of Creep and Long-Term Strength of Single-Crystal Refractory Nickel-Base Alloys

Microstructure evolution of a nickel-base single crystal superalloy during thermal exposure at 982°C was investigated. The SEM studies revealed that the size of γ' phase increased and some of which linked together with the elongation of the exposure time. There is acicular phase precipitation after the long-term ageing treatment. The TCP phase is not increased by the increment of ageing time after reaching a certain amount. There are skeleton shape carbides precipitate after 100h and 300h. The amount of precipitated carbides decreases by the elongation of ageing time.

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Structural and Phase Transformations in Single-Crystal Rhenium- and Ruthenium-Alloyed Nickel Alloy Under Testing For Long-Term Strength

Metal Science and Heat Treatment ◽

10.1007/s11041-015-9912-4 ◽

2015 ◽

Vol 57 (7-8) ◽

pp. 503-506

Author(s):

V. P. Kuznetsov ◽

V. P. Lesnikov ◽

I. P. Konakova ◽

N. A. Popov ◽

Yu. G. Kvasnitskaya

Keyword(s):

Single Crystal ◽

Phase Transformations ◽

Nickel Alloy ◽

Term Strength ◽

Structural And Phase Transformations ◽

Alloyed Nickel

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Long-Term Creep Property of a Second-Generation Nickel-Base Single-Crystal Superalloy, TMS-82+

Journal of the Japan Institute of Metals and Materials ◽

10.2320/jinstmet.69.743 ◽

2005 ◽

Vol 69 (8) ◽

pp. 743-746 ◽

Cited By ~ 6

Author(s):

Yutaka Koizumi ◽

Hiroshi Harada ◽

Toshiharu Kobayashi ◽

Tadaharu Yokokawa

Keyword(s):

Single Crystal ◽

Second Generation ◽

Creep Property ◽

Single Crystal Superalloy ◽

Nickel Base ◽

Term Creep

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The Rehbinder effect in tests of superalloys in contact with molten salts

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2021-87-10-54-62 ◽

2021 ◽

Vol 87 (10) ◽

pp. 54-62

Author(s):

L. B. Getsov ◽

M. Yu. Balandina ◽

A. I. Grishchenko ◽

A. B. Laptev ◽

A. I. Puzanov

Keyword(s):

Mechanical Properties ◽

Single Crystal ◽

Molten Salts ◽

Term Strength ◽

Initial State ◽

Rehbinder Effect ◽

Corrosive Media ◽

Term Operation ◽

Different Temperatures

The results of the Rehbinder effect manifestation during testing of superalloys in contact with corrosive media containing Na2SO4 + NaCl are discussed. We present the experimental study of the effect of salts containing chlorine and sulfur on the mechanical properties and long-term strength of single crystal and powder nickel-based superalloys at high temperatures. The practical value of the work is associated with the possible operation of gas turbine parts in conditions of ingress of the particles containing chlorine, sulfur and sodium into the flow path. A simplified (compared to a previously used) procedure of testing wrought alloys for long-term strength in molten salts is developed. A comparative study of the mechanical properties and long-term strength of a single crystal superalloy in the initial state (previously damaged by corrosion of different duration) and being in contact with salts during testing is carried out. Due to the large scatter of experimental data, the method of lower envelopes has been proposed and implemented to determine the guaranteed values of the long-term strength. It is shown that the guaranteed values of the long-term strength at different temperatures and test durations can decrease by 2.5 – 5.0 times in the presence of salts. Metallographic studies of the nature of damage and destruction of samples are carried out. The revealed decrease in the long-term strength of heat-resistant alloys in contact with salts is interpreted as the Rehbinder effect and not as a manifestation of the effect of stress corrosion cracking. A methodology for using the obtained test results with a duration of up to several thousand hours in highly aggressive environments is proposed to predict the long-term strength in relation to long-term operation (tens of thousands of hours) under conditions of relatively low salt loads.

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MODEL FOR PREDICTION OF HIGH TEMPERATURE DURABILITY OF CASTABLE NICKEL-BASE SUPERALLOYS

Proceedings of VIAM ◽

10.18577/2307-6046-2021-0-4-16-31 ◽

2021 ◽

pp. 16-31

Author(s):

N.V. Petrushin ◽

◽

Е.S. Elyutin ◽

Keyword(s):

Structural Phase ◽

Atomic Mass ◽

Term Strength ◽

Chemical Parameters ◽

Polycrystalline Nickel ◽

Physico Chemical ◽

Durability Prediction ◽

Nickel Base ◽

The Relationship

The relationship between the long-term strength and the structural-phase and physico-chemical parameters of castable polycrystalline nickel-based superalloys is considered. A regression model for prediction of the durability at a temperature of 1100 °C and a stress of 80 MPa of the considered class of alloys is proposed. The model takes into account the amount of the γ'-phase, the γ'-solvus and solidus temperatures, γ/γ'-misfit, the lattice spacing of the γ- and γ'-phases, and the atomic mass of the alloy. The reliability of the durability prediction is confirmed by comparison with the experimental results on the long-term strength at temperatures 1000, 1050 and 1100 °C of a number of industrial and experimental castable polycrystalline nickel-based superalloys.

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