scholarly journals The Effect of Grain Boundary Carbides on Dynamic Recrystallization During Hot Compression of Ni-Based Superalloy Haynes $$282^{\mathrm{TM}}$$

2021 ◽  
Author(s):  
Emil Eriksson ◽  
Joel Andersson ◽  
Magnus Hörnqvist Colliander
Keyword(s):  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Hot Compression ◽  
Boundary Phase ◽  
Stress Evolution ◽  
Critical Limit ◽  
Final Microstructure ◽  
Thermomechanical Processes ◽  
Base Superalloy

AbstractIn alloys where carbides are the main grain boundary phase, the role of carbides during hot working is not known. Here, we address the effect of grain boundary carbides on the dynamic recrystallization during hot compression of Ni-base superalloy Haynes 282. When excluding variations from experimental factors neither stress evolution nor final microstructure indicated that carbides exerted a significant influence on the dynamic recrystallization. The carbide solvus temperature is not a critical limit during thermomechanical processes.

Electrical Conductivity and Structure of Nanocrystalline CeO2 Thin Films

1996 ◽  
Vol 453 ◽  
Author(s):  
Igor Kosacki ◽  
Harlan U. Anderson
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Dominant Role ◽  
Boundary Phase ◽  
Electrical Measurements

AbstractThe results of structural and electrical measurements of nanocrystalline CeO2 thin films are presented. A correlation between the electrical conductivity and microstructure has been observed and discussed. The electrical properties of nanocrystalline CeO2 thin films are attributed to a dominant role of grain boundary phase.

Study on the Recrystallization Behavior of an as-Extruded PM Superalloy

2014 ◽  
Vol 529 ◽  
pp. 71-78 ◽  
Author(s):  
Shu Yun Wang ◽  
Yun Peng Dong ◽  
Min Cong Zhang ◽  
Chao Yuan Wang ◽  
Shuang Fang
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Dynamic Recrystallization ◽  
Interface Energy ◽  
Extrusion Temperature ◽  
Nickel Base Superalloy ◽  
Heat Temperature ◽  
Heat Treated ◽  
Nickel Base ◽  
Base Superalloy

The powder metallurgy (PM) nickel-base superalloy FGH96 was extruded at temperature from 1050°C to 1180°C,and the as-extruded samples in the extrusion temperature 1050°C were heat-treated at from 1000°C to 1100°C during 10min, 30min, 60min and 90min apart. The microstructure of recrystallization, γ' phase and growth behavior of grain were discussed. The results indicate that the extrusion temperature have a severely influence on the dynamic recrystallization and γ' phase behavior. The content and pattern of γ' phase is influenced by extrusion temperature and the big size of γ' phase in the grain boundary hinder effectively the growth of dynamic recrystallized grain. The degree of dynamic recrystallization is completed when the extrusion temperature increases. When the extrusion temperature reach 1100°C, the big size of γ' phase lie the grain boundary dissolves gradually and the grain grows obviously. As the heat temperature of as-extruded samples increases, the small size of γ' phase dissolves early and the degree of recrystallization is completed. When heat temperature reach 1080°C, the small size of γ' phase begin to dissolve and the recrystallization grain begins to grow, for the strain energy is given off and existence of interface energy. When heat temperature reach 1100°C, the recrystallization grain become uniform, for the pinning of big size of γ' phase. As the time of heat treatment elongate, the recrystallization grain size increase and the content of γ' phase decrease. When the heat temperature is 1080°C, the final microstructure is fine and uniform grain due to the pinning of big size of γ' phase. When the heat temperature is 1100°C, large of big size of γ' phase dissolve and the largest grain size reach 8μm. The nucleation and growth of recrystallization grain is influenced by small size of γ' phase and the fast growth of recrystallization grain is due to the big size of γ' phase in the grain boundary.

Effect of Thermomechanical Processes on Σ3 Grain Boundary Distribution in a Nickel Base Superalloy

2010 ◽  
Vol 638-642 ◽  
pp. 2333-2338
Author(s):  
Nadia Souaï ◽  
Roland E. Logé ◽  
Yvan Chastel ◽  
Nathalie Bozzolo ◽  
Vincent Maurel ◽  
...  
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Polycrystalline Materials ◽  
Nickel Base Superalloy ◽  
Grain Boundary Engineering ◽  
Thermomechanical Process ◽  
Grain Boundary Character ◽  
Nickel Base ◽  
Thermomechanical Processes ◽  
Base Superalloy

According to various studies, Grain Boundary Engineering (GBE) is likely to enhance mechanical properties of polycrystalline materials. The present investigation highlights some relationships between thermomechanical process (TMP) parameters of a commercial nickel-base superalloy PER72, supplied by Aubert & Duval (equivalent to Udimet®720™) and the resulting microstructure. The long-term goal is to develop TMPs that modify the Grain Boundary Character Distributions (GBCD) in order to improve high temperature properties. In this context, Grain Boundary Engineering (GBE) techniques are considered, thinking of replacing standard forming processes by optimised thermomechanical treatments. Mechanical testing at high temperature (compression and torsion tests) has been carried out and it is shown that multi-step treatments promote twinning. Some clues are then presented in an attempt to explain when and how twins are created.

The role of interfaces in the creep-deformation of a Sic whisker-reinforced Si3N4 composite

1990 ◽  
Vol 48 (4) ◽  
pp. 382-383
Author(s):  
K.L. More ◽  
D.A. Koester ◽  
R.F. Davis
Keyword(s):  
Grain Boundary ◽  
Nitrogen Atmosphere ◽  
Boundary Phase ◽  
Sintering Aids ◽  
X Ray Diffraction ◽  
High Temperature Mechanical Properties ◽  
Reinforced Composite ◽  
Linear Behavior ◽  
Transmission Electron

The high temperature mechanical properties of a SiC whisker-reinforced composite are currently being investigated. The deformation characteristics of the composite are controlled not only by the distribution of the constituent phases, but also by the interfaces between phases. The material is a hot pressed 30 vol.% SiC whisker-reinforced Si3N4 containing sintering aids of 1.5 wt.% A12O3 and 6.0 wt.% Y2O3. Constant compressive stress creep experiments were conducted in a continuously purified 0.11 MPa nitrogen atmosphere in a system described elsewhere. This work focussed on two creep experiments conducted at temperatures of 1470 K and 1620 K, both in the stress range 50-350 MPa. Figure 1 shows the stress exponent, n, for creep of the composite at both 1470 K and 1620 K. At 1620 K, n exhibited a bi-linear behavior. However, this behavior was not observed for creep at 1470 K.In the as-hot pressed state, the composite had an amorphous grain boundary phase containing N, O, Al, Si, and Y as determined by energy dispersive spectroscopy. Prior to loading, the specimens were annealed for 4 hr at the creep temperature. During the anneal, the grain boundary phase crystallized and underwent a change in composition as determined by X-ray diffraction and transmission electron microscopy (TEM).

The role of long period stacking ordered phase in dynamic recrystallization of a Mg–Zn–Y alloy during hot compression

2020 ◽  
Vol 818 ◽  
pp. 152814 ◽  
Author(s):  
Tao Chen ◽  
Zhiyong Chen ◽  
Jianbo Shao ◽  
Renke Wang ◽  
Longhui Mao ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Compression ◽  
Long Period

The Role of Glassy Grain Boundary Phases in the Microwave Joining of Alumina

1994 ◽  
Vol 347 ◽  
Author(s):  
Pamela Davis ◽  
Jon Binner ◽  
Tom Cross ◽  
John Fernie
Keyword(s):  
Dielectric Loss ◽  
Grain Boundary ◽  
Resonant Cavity ◽  
Single Mode ◽  
Alumina Ceramic ◽  
Boundary Phase ◽  
Alumina Ceramics ◽  
Axial Pressure ◽  
Individual Grains

ABSTRACTThe role of intergranular glassy phases in the microwave joining of alumina ceramic rods has been investigated. Alumina ceramics of different purities have been examined using a TE102 single mode rectangular resonant cavity operating at 2.45 GHz. Temperature and axial pressure were varied and the resultant join microstructures analyzed. The presence of a glassy grain boundary phase has been shown to improve the ability to microwave join alumina ceramics by increasing the dielectric loss of the ceramic and, when softened, by enabling the alumina grains to flow under the imposed load. Evidence has also been found for the sintering of individual grains where they have come into contact across the join line.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

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