Grain Growth Impediment of Fe-Based Nanocomposites During Heat Treatment at Elevated Temperature

1995 ◽  
Vol 400 ◽  
Author(s):  
B. Huang ◽  
R.J. Perez ◽  
E.J. Lavernia
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Ostwald Ripening ◽  
Nanocrystalline Structure ◽  
Liquid Argon ◽  
High Thermal Stability ◽  
Additional Stabilization ◽  
Nanocrystalline Microstructure

AbstractCryogenic ball milling of Fe-10 wt.%Al in liquid argon is shown to produce a nanocrystalline microstructure with high thermal stability against grain growth. The experimental evidence suggests that this stability may originate from the presence of fine γ-Al2O3 particles which pin the Fe grain boundaries. In contrast, Fe3O4 particles formed during cryomilling of Fe in liquid nitrogen were not able to impede grain growth during consolidation at 823 K. The interactions between the γ-Al2O3 particles and the grain boundaries during growth may be described by Gladman's theory. Additional stabilization against grain growth may have been provided by the presence of Al at the Fe grain boundaries. Following annealing at 1223 K, the grain size of the Fe-10 wt.%Al powders cryomilled in liquid argon was 13.3 ± 7.9 nm, but it exceeded 1700 nm following annealing at 1373 K. The loss of nanocrystalline structure may be attributed to the Ostwald ripening of γ-Al2O3 particles, resulting in abnormal grain growth.

The Impact of Pre-Silicidation Heat Treatment and Dopant Effects on the Thermal Stability of Cosi2 Polycide During Rapid Thermal Annealing

1993 ◽  
Vol 303 ◽  
Author(s):  
W. Chen ◽  
J. Lin ◽  
S. Banerjee ◽  
J. Lee
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Ion Implantation ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Silicon Substrate ◽  
Amorphous Si ◽  
Si Films ◽  
The Impact ◽  
Thermal Stability Of

ABSTRACTThe effects of heat treatment of polysilicon and amorphous Si films on their microstructure and thermal stability of polycides formed on these films have been studied. The number of grain boundaries decreases after pre-silicidation heat treatment in polysilicon due to grain growth but increases in amorphous Si due to nucleation. Since the thermal stability of CoSi2 polycide films was found to be closely related to the number of grain boundaries in the underlying silicon substrate, pre-silicidation heat treatments degrade the thermal stability of CoSi2 on as-deposited amorphous Si and improve the thermal stability of CoSi2 on asdeposited polysilicon. Doping does not have as pronounced an effects as substrate microstructure on CoSi21 polycide thermal stability, especially when dopants are introduced after silicidation by ion implantation.

Effect of Pre-Strain Rolling on Annealing Behavior of Friction-Stir Welded AA6061-T6 Aluminum Alloy

2018 ◽  
Vol 385 ◽  
pp. 355-358 ◽  
Author(s):  
Sergey Mironov ◽  
Sergey Malopheyev ◽  
Igor Vysotskiy ◽  
Daria Zhemchuzhnikova ◽  
Rustam Kaibyshev
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Aluminum Alloy ◽  
Cold Rolling ◽  
Grain Growth ◽  
Rolling Schedule ◽  
Annealing Behavior ◽  
Friction Stir ◽  
Welding Direction ◽  
Thermal Stability Of

In this work, the effect of pre-strain cold rolling on thermal stability of friction-stir welded AA6061-T6 alloy was studied. The pre-strain rolling was found to be very effective in suppression of abnormal grain growth during standard post-weld T6 heat treatment. It was also shown that the efficiency of this approach essentially depends on rolling path and the rolling along welding direction was the most effective rolling schedule.

scholarly journals The Influence of Holding Time on the Microstructure Evolution of Mg–10Zn–6.8Gd–4Y Alloy during Semi-Solid Isothermal Heat Treatment

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 420 ◽  
Author(s):  
Shuang Nie ◽  
Bingyang Gao ◽  
Xuejian Wang ◽  
Zhiqiang Cao ◽  
Enyu Guo ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Boundaries ◽  
Microstructure Evolution ◽  
Treatment Process ◽  
Ostwald Ripening ◽  
Eutectic Structure ◽  
Holding Time ◽  
Isothermal Heat Treatment ◽  
Heat Treatment Process ◽  
Semi Solid

A semi-solid microstructure of Mg–10Zn–6.8Gd–4Y alloys is acquired via an isothermal heat treatment process, and the effects of the holding time on the microstructure evolution of Mg–10Zn–6.8Gd–4Y alloys are investigated. The results show that the microstructure of the cast alloy is composed of primary α-Mg dendritic grains with a eutectic structure (W-phase and eutectic Mg) distributed at the grain boundaries. The primary α-Mg dendritic grains grow in size with increasing holding time, and they tend to grow into more globular structures in the initial stage; they then become a bit more dendritic, as small branches grow from the grain boundaries after holding the sample at 580 °C for 10 min. Meanwhile, the interdiffusion of magnesium atoms within the eutectic region, and between the primary α-Mg and eutectic structure, leads to the formation of fine and relatively globular eutectic Mg grains in the eutectic structure after holding for 10 min. The eutectic Mg grains begin to grow, coarsen, coalesce, or be swallowed by the surrounding primary grains, causing fluctuations of the general grain size. Over the whole isothermal heat treatment process, two mechanisms—coalescence and Ostwald ripening—dominate the grain coarsening.

TOUGHMET 2

Alloy Digest ◽  
2013 ◽  
Vol 62 (5) ◽  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Fracture Toughness ◽  
Wear Resistance ◽  
High Performance ◽  
Mechanical Performance ◽  
High Thermal Stability ◽  
Lead Free ◽  
Plain Bearing ◽  
Ni Alloy

Abstract ToughMet 2 is a high performance, wrought, heat treatable, lead-free strip Cu-Ni alloy that imparts superior mechanical performance and high thermal stability to plain bearing applications. Parts are easily formed and they can be machined either before or after heat treatment. ToughMet alloys are a line of spinodal hardened Cu-Ni anti-galling alloys for bearings capable of performing with a variety of shafting materials and lubricants. The alloys combine a high lubricity with wear resistance in these severe loading conditions. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on corrosion resistance as well as forming and machining. Filing Code: Cu-724. Producer or source: Materion Brush Performance Alloys. Originally published September 2004, revised May 2013.

scholarly journals Scanning 3DXRD Measurement of Grain Growth, Stress, and Formation of Cu6Sn5 around a Tin Whisker during Heat Treatment

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 446 ◽  
Author(s):  
Johan Hektor ◽  
Stephen Hall ◽  
N. Henningsson ◽  
Jonas Engqvist ◽  
Matti Ristinmaa ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Hydrostatic Stress ◽  
Coincidence Site Lattice ◽  
Sample Surface ◽  
Growth Stress ◽  
Projection Algorithm ◽  
Tin Whisker ◽  
Tin Coating

The 3D microstructure around a tin whisker, and its evolution during heat treatment were studied using scanning 3DXRD. The shape of each grain in the sample was reconstructed using a filtered-back-projection algorithm. The local lattice parameters and grain orientations could then be refined, using forward modelling of the diffraction data, with a spatial resolution of 250 n m . It was found that the tin coating had a texture where grains were oriented such that their c-axes were predominantly parallel to the sample surface. Grains with other orientations were consumed by grain growth during the heat treatment. Most of the grain boundaries were found to have misorientations larger than 15 ∘ , and many coincidence site lattice (CSL) or other types of low-energy grain boundaries were identified. None of the grains with CSL grain boundaries were consumed by grain growth. During the heat treatment, growth of preexisting Cu6Sn5 occurred; these grains were indexed as a hexagonal η phase, which is usually documented to be stable only at temperatures exceeding 186 ∘ C . This indicates that the η phase can exist in a metastable state for long periods. The tin coating was found to be under compressive hydrostatic stress, with a negative gradient in hydrostatic stress extending outwards from the root of the whisker. Negative stress gradients are generally believed to play an essential role in providing the driving force for diffusion of material to the whisker root.

Thermal Stability and Mechanical Properties of Plasma Sprayed Al2O3/ZrO2 Nano-Composite Coating

2006 ◽  
Vol 317-318 ◽  
pp. 513-516 ◽  
Author(s):  
Satoshi Sodeoka ◽  
Masato Suzuki ◽  
Takahiro Inoue
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Composite Coating ◽  
Grain Growth ◽  
Nano Composite ◽  
Good Thermal Stability ◽  
Fine Powders ◽  
Nano Composite Coating ◽  
Plasma Sprayed

Alumina/zirconia nano-composite coating was fabricated by plasma spraying using agglomerated feedstock from fine powders of about 100 nm. The coating was consisted of fine γ-alumina and zirconia crystals with size of several nano meter and some amorphous boundary layers. The amorphous phase was crystallized and disappeared after heat treatment at 930°C. However, the crystallite size was kept under 50 nm even after 1500°C-100hr heating, so the alumina-zirconia nano-composite showed good thermal stability against the grain growth.

Formation of in situ reinforced microstructures in α-sialon ceramics: Part III. Static and dynamic ripening

2004 ◽  
Vol 19 (8) ◽  
pp. 2402-2409 ◽  
Author(s):  
Hong Peng ◽  
Zhijian Shen ◽  
Mats Nygren
Keyword(s):  
Heat Treatment ◽  
Grain Growth ◽  
Liquid Glass ◽  
Glass Phase ◽  
Ostwald Ripening ◽  
Graphite Furnace ◽  
Stoichiometric Composition ◽  
Temperature Threshold ◽  
Post Heat Treatment

Dual cation (Yb + Y)-stabilized α-sialon ceramics with either stoichiometric composition or nonstoichiometric composition that yield less than 3 vol% of an additional intergranular liquid/glass phase were consolidated by spark plasma sintering (SPS). This process allows very fast heating and cooling, thus providing a unique possibility to monitor and manipulate the kinetics of phase transformation and grain growth during sintering. Below a temperature threshold, full densification and complete α-sialon formation are accompanied by very limited grain growth. The grain growth kinetics were investigated both by post heat-treatment of SPS pre-consolidated monophasic α-sialon bodies consisting of sub-micron sized equiaxed grains in a conventional graphite furnace using extended holding times (hours) and directly rapid annealing in the SPS apparatus above the temperature threshold (within minutes). Post heat treatment in the graphite furnace yielded in situ reinforced microstructures consisting of interlocking elongated grains only in the presence of an additional intergranular liquid/glass phase. Direct annealing by SPS process yielded in situ reinforced microstructures whether or not an additional liquid/glass was involved. The former microstructures are formed via the static Ostwald ripening mechanism whereas the latter ones are generated via a dynamic ripening mechanism. This demonstrates that the dynamic ripening provides an efficient means of developing in situ reinforced microstructure in α-sialon ceramics with improved mechanical properties.

scholarly journals Thermostable Adenosine 5’-Monophosphate Phosphorylase from Thermococcus kodakarensis forms catalytically active inclusion bodies

2020 ◽  
Author(s):  
Sarah Kamel ◽  
Miriam Walczak ◽  
Felix Kaspar ◽  
Sarah Westarp ◽  
Peter Neubauer ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Inclusion Bodies ◽  
Specific Activity ◽  
High Thermal Stability ◽  
Active Protein ◽  
E Coli ◽  
Thermococcus Kodakarensis ◽  
Active Inclusion Bodies ◽  
Catalytically Active

Abstract Catalytically active inclusion bodies (CatIBs) produced in E. coli are an interesting but currently underexplored strategy for enzyme immobilization. They can be purified easily and used directly as stable and reusable heterogenous catalysts. However, very few examples of CatIBs that are naturally formed during heterologous expression have been reported so far. Previous studies have revealed that the adenosine 5'-monophosphate phosphorylase of Thermococcus kodakarensis (TkAMPpase) forms large soluble multimers with high thermal stability. Herein, we show that heat treatment of solubilized protein induces aggregation of active protein which phosphorolysis all natural 5’-mononucleotides. Additionally, inclusion bodies formed during the expression in E. coli were found to be similarly active with 2−6 folds higher specific activity compared to the heat-induced aggregates. Interestingly, differences in the substrate preference were observed. These results show that the recombinant thermostable TkAMPpase is one of rare examples of naturally formed CatIBs.

Sign in / Sign up

Export Citation Format

Share Document