scholarly journals Microstructure Development in Additive Friction Stir-Deposited Cu

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1538
Author(s):  
Jonathan L. Priedeman ◽  
Brandon J. Phillips ◽  
Jessica J. Lopez ◽  
Brett E. Tucker Roper ◽  
B. Chad Hornbuckle ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Microstructure Evolution ◽  
Vickers Hardness ◽  
Work Hardening ◽  
Surface Oxide ◽  
Microstructure Development ◽  
Friction Stir ◽  
Grain Sizes

This work details the additive friction stir-deposition (AFS-D) of copper and evaluation of its microstructure evolution and hardness. During deposition, a surface oxide is formed on the deposit exterior. A very fine porosity is formed at the substrate–deposit interface. The deposit (four layers of 1 mm nominal height) is otherwise fully dense. The grains appear to have recrystallized throughout the deposit with varying levels of refinement. The prevalence of twinning was found to be dependent upon the grain size, with larger local grain sizes having a higher number of twins. Vickers hardness measurements reveal that the deposit is softer than the starting feedstock. This result indicates that grain refinement and/or higher twin densities do not replace work hardening contributions to strengthen Cu processed by additive friction stir-deposition.

Effect of Solute Elements on Grain Refinement during Friction Stir Processing in High-Purity Aluminum

2016 ◽  
Vol 838-839 ◽  
pp. 116-121 ◽  
Author(s):  
Tokuteru Uesugi ◽  
Hideaki Iwami ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Friction Stir Processing ◽  
High Purity ◽  
Critical Role ◽  
Hollomon Parameter ◽  
Friction Stir ◽  
Grain Sizes ◽  
Purity Level ◽  
High Purity Aluminum

Friction stir processing (FSP) is one of the severe plastic deformation (SPD) processes. It has been reported that SPD-processed Al with various purities attained a minimum grain size when Zener-Hollomon parameter is larger than 1016 s-1. The minimum grain size is different by purity level and alloying elements. We investigated the influence of Fe solute atoms on grain refinement of high-purity Al on the condition that Zener-Hollomon parameter was larger than 1016 s-1. FSP was conducted on Al-0.01%Fe, which was fabricated by using 5N Al (99.999% purity). FSP-ed Al-0.01%Fe exhibits the minimum grain size of 1.4 μm, although high-purity aluminums with more than 99.998% exhibits much larger minimum grain sizes of 30-40 μm. Only 101 at.ppm Fe played a critical role in the grain refinement of pure aluminums.

scholarly journals Mechanical and Electrical Characteristics of WB2 Synthesized at High Pressure and High Temperature

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1212 ◽  
Author(s):  
Changchun Wang ◽  
Lele Song ◽  
Yupeng Xie
Keyword(s):  
Grain Size ◽  
High Pressure ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Vickers Hardness ◽  
Single Phase ◽  
Hard Material ◽  
Experimental Conditions ◽  
Boundary Density ◽  
Grain Sizes

Single-phase tungsten diboride (WB2) was synthesized at high pressure and high temperature. The different grain sizes ranging from 300 nm to 3 µm were successfully obtained in WB2 by controlling the experimental conditions. The effects of grain size on hardness and resistivity properties were investigated. The Vickers hardness of WB2 was modulated with grain size. The maximum asymptotic Vickers hardness is 25.5 GPa for WB2 with a grain size of 300 nm which is a 10% increase compared to WB2 with a grain size of 3 µm. The optimal electrical resistivity of WB2 was 10−7 Ωm with the biggest grain size of 3 µm, which is ascribed to low grain boundary density. The superior properties of hardness and electrical resistivity demonstrate that WB2 should be a new functional hard material replacing WC which is widely used in industrial production.

The Characteristic Grain Size and the Compressive Strength of Ice Containing a Bimodal Distribution of Grain Sizes

1989 ◽  
Vol 111 (1) ◽  
pp. 61-62
Author(s):  
E. M. Schulson ◽  
J. L. Laughlin
Keyword(s):  
Grain Size ◽  
Compressive Strength ◽  
Grain Refinement ◽  
Bimodal Distribution ◽  
Grain Sizes ◽  
Freshwater Ice ◽  
Polycrystalline Ice

The purpose of this communication is to show through experiment that the compressive strength of polycrystalline ice, which contains a bimodal distribution of grain sizes, can be expressed in terms of a characteristic grain size. The work was performed in response to an awareness that grain refinement strengthens both columnar [1] and granular [2] freshwater ice deformed under compression, and that ice formed naturally often contains grains of more than one size. A detailed discussion is given elsewhere [3].

Effect of Strain-Hardening Induced Grain Refinement on Springback in Microtube Press Bending Process

2012 ◽  
Vol 528 ◽  
pp. 111-118
Author(s):  
Cho-Pei Jiang
Keyword(s):  
Grain Size ◽  
Strain Hardening ◽  
Grain Refinement ◽  
Microstructure Development ◽  
Bending Angle ◽  
The Press ◽  
Bending Process ◽  
Twin Band ◽  
Three Stages ◽  
Springback Behavior

Seamless stainless microtube (SUS 304L) was selected for a detailed investigation of the strain-hardening influencing grain refinement and microstructural evolution during processing by varying press bending angles. The problem was approached in three stages. First, the microtubes were annealed to examine the initial grain size and analyzed the effect of grain size on mechanical properties by performing a tensile test. Second, a microtube press bending system was developed to observe springback behavior. Third, the microstructure of the microtube with different press bending angle was observed to investigate the effect of strain-hardening induced grain refinement on springback behavior. As a result, the occurrence of grain refinement reduced the springback amount. The mechanism of microstructure development in the shear zone during the press bending process is needle like, twin band and equiaxed and small rounded grains sequentially.

Features of Work Hardening of Polycrystals with Nanograins

2008 ◽  
Vol 584-586 ◽  
pp. 35-40 ◽  
Author(s):  
Eduard Kozlov ◽  
Nina Koneva ◽  
L.I. Trishkina ◽  
A.N. Zhdanov ◽  
M.V. Fedorischeva
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Work Hardening ◽  
Mechanical Characteristics ◽  
Grain Boundary Sliding ◽  
Deformation Mechanisms ◽  
Dislocation Slip ◽  
Grain Sizes ◽  
Boundary Sliding ◽  
Size Interval

The present work is devoted to the investigation of the influence of the grain size on the main mechanical characteristics of nanopolycrystals of different metals. The Hall-Petch parameter behaviour for Al, Cu, Ni, Ti and Fe was examined in the wide grain size interval. The stages of plastic deformation and the parameters of work hardening for nanocrystalline copper were analysed in detail. The deformation mechanisms and critical grain sizes accounting for the transition from the dislocation slip to the grain boundary sliding were described.

Microstructure Evolution in Magnesium Alloy ZK60 during Cyclic Extrusion and Compression

2014 ◽  
Vol 1035 ◽  
pp. 259-262
Author(s):  
Fei Han ◽  
Hong Wei Liu ◽  
Gang Chen
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Microstructural Evolution ◽  
Microstructure Evolution ◽  
Extrusion Ratio ◽  
Technical Parameters ◽  
Average Grain Size ◽  
Zk60 Magnesium Alloy ◽  
Refinement Effect

The microstructural evolution of of as-cast ZK60 magnesium alloy processed by cyclic extrusion and compression (CEC) were studied, and the effects of technical parameters on microstructural evolution were investigated. The results show that the grains of as-cast ZK60 magnesium alloy were obviously refined and uniformed by CEC, the average grain size was decreased from original 50 ~ 60 μm to about 2 μm when the extrusion ratio was 8 with 8-passes at 350°C, and the refinement effect was increased with the rising of extrusion ratio and passes. The effect of increasing passes on grain refinement was not obvious when it exceeds 8. Nevertheless, it is beneficial for the grain homogenization.

Transition from Superplastic Behavior - Viscous Glide - Dislocation Climb - Power-Law Break down Regimes in Friction Stir Processed AA5083

2016 ◽  
Vol 863 ◽  
pp. 23-30
Author(s):  
Ehab A. El-Danaf ◽  
Mahmoud Soliman ◽  
Magdy M. El Rayes
Keyword(s):  
Grain Size ◽  
Feed Rate ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Lattice Diffusion ◽  
Al Alloy ◽  
Experimental Conditions ◽  
Friction Stir ◽  
Grain Sizes ◽  
True Activation Energy

5083 Al alloy was friction stir processed (FSP) at room temperature under various experimental conditions. Two rotational speeds of 430 and 850 rpm with a single traverse feed of 90 mm/min (430-90, 850-90) were used, to investigate the effect of rotation speed. Also, another feed rate of 140 mm/min was used with a rotational speed of 430 rpm (430-140), to investigate the effect of feed rate. The processing conditions resulted in three different grain sizes of 0.95, 1.6 and 2.6 μm depending on the FSP parameters. The deformation behavior of the FSP samples was investigated at 250 C at three strain rates of 10-4, 10-3 and 10-2 s-1. The values of strain rate sensitivity, m was determined, as a function of grain size, and it decreased from 0.45 to 0.33 to 0.18 with increasing the grain size. True activation energy was calculated as 63, 95, 157 kJ/mole for the grain sizes of 0.95, 1.6 and 2.6 μm, respectively. These calculated values are comparable to grain boundary sliding of magnesium in aluminum (69 – 78 kJ mol-1), magnesium in aluminum (~115 kJ mole-1) and aluminum lattice diffusion (~143 kJ mol-1 ). The change in the deformation mechanism with grain size was discussed in some details.

Microstructure Evolution in Undercooled Ni-Si Melt

2013 ◽  
Vol 749 ◽  
pp. 349-355
Author(s):  
Kai Fan ◽  
Feng Liu ◽  
Bao Quan Fu ◽  
Wen Zhong Luo ◽  
Yao He Zhou
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Grain Refinement ◽  
Microstructure Evolution ◽  
Solid Solubility ◽  
Molten Glass ◽  
Dendrite Fragmentation ◽  
Equilibrium Solidification ◽  
Good Agreement ◽  
Non Equilibrium

Upon non-equilibrium solidification, the intrinsic parameters, such as moving velocity, temperature, solute partition coefficient, and liquid and solid concentrations at the interface, deviate from their equilibrium characteristics, and the morphology of the as-solidified structure and the grain size are influenced by the non-equilibrium liqulid/solid transformation, which further influences the subquent solidstate transformation. Adopting molten glass purification technology combined with cycle superheating method, the microstructure evolution of Ni-11at.%Si alloy in different undercooling was investigated. It was found that, with the increase of the initial undercooling, grain refinement occurred in microstructures of undercooled Ni-11at.%Si alloy. Meanwhile, the NL model was used to discuss the two different dendrite morphologies. According to Karmas model for dendrite fragmentation, the grain refinement of undercooled Ni-11at.%Si alloy was in good agreement with the experimental data, and the grain size was reduced with the increasing ΔT. The energy-dispersive spectroscopy (EDS) measurement was applied to analyze the solid solubility of Si atom in α-Ni matrix. It was found that the solid solubility of Si atom in α-Ni matrix increased with undercooling. At the undercooling of T>220K , a complete solute trapping occurred.

scholarly journals Microstructure, hardness and wear resistance of AZ91 magnesium alloy produced by friction stir processing with air cooling

2021 ◽  
Author(s):  
Józef Iwaszko ◽  
Krzysztof Kudła
Keyword(s):  
Wear Resistance ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Friction Stir Processing ◽  
Vickers Hardness ◽  
Air Cooling ◽  
Az91 Magnesium Alloy ◽  
Friction Stir ◽  
Jet Cooling ◽  
Az91 Magnesium

Abstract Friction stir processing (FSP) was used to modify the surface layer of the AZ91 magnesium alloy. The treatment was carried out using a jet cooling nozzle, generating a stream of cold air and enabling intensive cooling of the friction stir processed (FSPed) zone. Single-pass FSP was carried out using a tool rotational speed of 500 rpm and travel speed of 30 mm/min. The treatment was conducted using a truncated cone-shaped tool with a threaded side surface. Strong grain refinement and microstructural changes typical for FSP were found in all the samples. Very fine, equiaxed recrystallized grains dominated in the stirring zone. In the samples modified with the jet cooling nozzle, greater grain refinement was obtained than in the case of naturally-cooled material. The average grain size in the surface part of the stirring zone was 1.4 µm and 9 µm in the samples with air cooling and with natural cooling, respectively. Both the naturally-cooled specimen and air-cooled specimen were characterized by a distinctly higher hardness than the base material. The average Vickers hardness in the stirring zone was 91 HV0.1 in the FSPed sample with the air-cooling system and 85.5 HV0.1 with natural cooling, respectively. The average Vickers hardness of the as-cast alloy was 64 HV0.1. Slightly higher wear resistance of the FSPed samples using a jet cooling nozzle was found in relation to the naturally-cooled sample. Based on the conducted research, high efficiency of the jet cooling nozzle in cooling the modified zone during friction stir processing was found.

scholarly journals The Effect of Friction Stir Processing (FSP) on the Microstructure and Properties of AM60 Magnesium Alloy

2016 ◽  
Vol 61 (3) ◽  
pp. 1555-1560 ◽  
Author(s):  
J. Iwaszko ◽  
K. Kudła ◽  
K. Fila ◽  
M. Strzelecka
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Friction Stir Processing ◽  
Structural Changes ◽  
Flow Line ◽  
Homogeneous Microstructure ◽  
X Ray ◽  
Friction Stir ◽  
Average Grain Size

Abstract The samples of the as-cast AM60 magnesium alloy were subjected to Friction Stir Processing (FSP). The effect of FSP on the microstructure of AM60 magnesium alloy was analyzed using optical microscopy and X-ray analysis. Besides, the investigation of selected properties, i.e. hardness and resistance to abrasion wear, were carried out. The carried out investigations showed that FSP leads to more homogeneous microstructure and significant grain refinement. The average grain size in the stirred zone (SZ) was about 6-9 μm. in the thermomechanically affected zone (TMAZ), the elongated and deformed grains distributed along flow line were observed. The structural changes caused by FSP lead to an increase in microhardness and wear resistance of AM60 alloy in comparison to their non-treated equivalents. Preliminary results show that friction stir processing is a promising and an effective grain refinement technique.

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