Improvement of high-temperature creep resistance in fine-grained Al2O3 by Zr4+ segregation in grain boundaries

1997 ◽  
Vol 76 (1) ◽  
pp. 9-14 ◽  
Author(s):  
H. Yoshida ◽  
K. Okada ◽  
Y. Ikuhara ◽  
T. Sakuma
Keyword(s):  
High Temperature ◽  
Grain Boundaries ◽  
Creep Resistance ◽  
High Temperature Creep ◽  
Fine Grained ◽  
Temperature Creep

High-temperature Creep Resistance in Rare-earth-doped, Fine-grained Al2O3

1998 ◽  
Vol 13 (9) ◽  
pp. 2597-2601 ◽  
Author(s):  
H. Yoshida ◽  
Y. Ikuhara ◽  
T. Sakuma
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Grain Boundaries ◽  
Creep Resistance ◽  
Rare Earth Oxide ◽  
Rare Earth Ions ◽  
Second Phase ◽  
High Temperature Creep ◽  
Fine Grained ◽  
Temperature Creep

High-temperature creep in undoped Al2O3 and La2O3- or Y2O3- or Lu2O3-doped Al2O3 with a grain size of about 1 µm is examined in uniaxial compression testing at temperatures between 1150 and 1350 °C. The high-temperature creep resistance in Al2O3 is highly improved by the rare-earth oxide doping in the level of 0.045 mol %, and the creep rate is suppressed in the order La2O3 <Y2O3 <Lu2O3. Rare-earth ions in each doped Al2O3 are found to segregate in Al2O3 grain boundaries without forming amorphous phase or second-phase particles. The activation energy for creep in undoped Al2O3 is estimated to be 410 kJ/mol, while it is about 800 kJ/mol in the three rare-earth oxide-doped Al2O3. The grain boundary diffusivity must be highly reduced by the segregation of the dopant cation in Al2O3 grain boundaries.

Analysis of Cracking Process in Conditions of High-Temperature Creep of Castings Form the Modified Superalloy IN-713C

2013 ◽  
Vol 212 ◽  
pp. 247-254
Author(s):  
Marek Cieśla ◽  
Franciszek Binczyk ◽  
Marcin Mańka
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Nickel Superalloy ◽  
Morphological Properties ◽  
Coarse Grain ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Fine Grain ◽  
Initiation And Propagation ◽  
Cracking Process

mpact of complex modification and filtration during pouring into moulds on durability has been evaluated in this study in conditions of high-temperature creep of castings made from nickel superalloy IN-713C post production rejects. The conditions of initiation and propagation of cracks in the specimens were analysed with consideration of morphological properties of material macro-, micro-and substructure. It has been demonstrated that in conditions of high-temperature creep at temperature 980°C with stress σ =150 MPa creep resistance of the IN-713C superalloy increases significantly with the increase of macrograin size. Creep resistance of specimens made of coarse grain material was significantly higher than the resistance of fine grain material.

Fe–Co–V alloy with improved magnetic properties and high-temperature creep resistance

2003 ◽  
Vol 93 (10) ◽  
pp. 7118-7120 ◽  
Author(s):  
S. Liu ◽  
S. Bauser ◽  
Z. Turgut ◽  
J. Coate ◽  
R. T. Fingers
Keyword(s):  
Magnetic Properties ◽  
High Temperature ◽  
Creep Resistance ◽  
High Temperature Creep ◽  
Temperature Creep

Microanalysis for Design and Development of Improved High-Temperature Alloys

2001 ◽  
Vol 7 (S2) ◽  
pp. 544-545
Author(s):  
Philip J. Maziasz
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Power Plants ◽  
Austenitic Stainless Steels ◽  
High Temperature Creep ◽  
Alloy Development ◽  
Temperature Creep ◽  
Microstructural Design ◽  
Engineering Alloys ◽  
Processing Optimization

Alloy development can range from purely empirical, trial-and-error efforts to very theoretical, based on either fundamental first-principles calculations or computational-modeling using various kinds of data base inputs. However, “real-world” efforts to improve or optimize complex engineering alloys often cannot afford the time or cost of either extreme approach. in the past 10-15 years, an alloy development and processing optimization methodology has been developed that utilizes strategic microanalytical data (both detailed microstucture and microcompositional information) as the critical input that then enables efficient and effective design of various kinds of alloys for improved high-temperature performance [1-6]. in many cases, first time tests produce outstanding high-temperature creep or creep-rupture results, and enable improvements without trading off one property for another. This invited paper will highlight several examples of significantly improved creep resistance obtained using such microstructural design.This microstructural design methodology for high-temperature creep-resistance was initially developed for and demonstrated in austenitic stainless steels (Fe-14Cr-16Ni) designed for improved creep-strength and rupture resistance at 700°C and above for superheater and boiler tubing in advanced fossil power plants.

The Effect of Heat Treatment on Creep Resistance of Castings from the Modified Superalloy MAR-247

2013 ◽  
Vol 212 ◽  
pp. 229-236
Author(s):  
Marek Cieśla ◽  
Franciszek Binczyk ◽  
Marcin Mańka
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Creep Resistance ◽  
Nickel Superalloy ◽  
Grain Structure ◽  
Morphological Properties ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Fine Grain ◽  
Heat Treated

mpact of heat treatment on durability has been evaluated in this study in conditions of high-temperature creep of castings made from nickel superalloy MAR-247 post production rejects. Castings made in the processes of modification and filtration when pouring into moulds were subject to solubilization (1185°C/2 h) with subsequent ageing (870°C/20 h). It has been found on the basis of performed tests that in conditions of high-temperature creep at temperature 980°C with stress σ = 150 MPa the resistance of specimens of coarse-grain structure was significantly higher when compared to fine-grain material. The conditions of initiation and propagation of cracks in these specimens were analysed with consideration of morphological properties of material macro-, micro-and substructure. Moreover, it has been proven that creep resistance of heat treated MAR-247 superalloy significantly improves when compared to its condition after the process of modification only. Macrostructural changes in the MAR-247 superalloy that determine the increase of superalloy creep resistance after solubilization and ageing, as observed in the tests, were also examined.

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