Investigating the Relationships Between Structures and Properties of Al Alloys Incorporated With Ti and Mg Inclusions

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Halil Ibrahim Kurt ◽  
Ibrahim H. Guzelbey ◽  
Serdar Salman ◽  
Razamzan Asmatulu ◽  
Mustafa Dere
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Elevated Temperatures ◽  
Solidification Process ◽  
Optical Microscope ◽  
Industrial Applications ◽  
Al Alloys ◽  
Average Grain Size ◽  
Solidification Processes ◽  
Grain Size And Shape

This study investigates the influence of titanium (Ti) and magnesium (Mg) additions on aluminum (Al) alloys in order to evaluate the relationship between the structure and properties of the new alloys. The alloys obtained at elevated temperatures mainly consist of Al–2Mg–1Ti, Al–2Mg–3Ti, Al–4Mg–2Ti, and Al–6Mg–2Ti alloys, as well as α and τ solid solution phases of intermetallic structures. Microstructural analyses were performed using X-ray diffraction (XRD), optical microscope, and energy dispersive spectrometry (EDS) techniques. Test results show that the average grain size of the alloys decreased with the addition of Ti inclusions during the casting and solidification processes, and the smallest grain size was found to be 90 μm for the Al–6Mg–3Ti alloy. In addition, tensile properties of the Al–Mg–Ti alloys were initially improved and then worsened after the addition of higher concentrations of Ti. The highest tensile and hardness values of the alloys were Al–4Mg–2Ti (205 MPa) and Al–6Mg–3Ti (80 BHN). The primary reasons for having higher mechanical properties may be attributed to strengthening of the solid solution and refinement of the grain size and shape during the solidification process. For this study, the optimum concentrations of Ti and Mg added to the Al alloys were 4 and 2 wt.%, respectively. This study may be useful for field researchers to develop new classes of Al alloys for various industrial applications.

Grain Structure and Surface Roughness of Four Commercial NiTi Orthodontic Archwires

2017 ◽  
Vol 266 ◽  
pp. 257-263
Author(s):  
Wassana Wichai ◽  
Rutchadakorn Isarapatanapong ◽  
Niwat Anuwongnukroh ◽  
Surachai Dechkunakorn
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Optical Microscope ◽  
Grain Structure ◽  
Wire Surface ◽  
Average Grain Size ◽  
Electron Mode ◽  
The Mean ◽  
The Wire ◽  
Orthodontic Archwires

This study investigated four commercially available NiTi orthodontic archwires from different manufactures for their grain structure and surface roughness.Four commercially available pre-formed NiTi orthodontic archwire (Ormco, Sentalloy, Highland and NIC) with diameter 0.016 x 0.022 inch2 were tested. The wire samples were polished and etched to evaluate the morphology and structure of wire surface. Each NiTi archwire was investigated under a reflected light microscope of an Optical Microscope to analyze its grain structure and size, in longitudinal surfaces. The surfaces of wire were qualitatively examined in the secondary electron mode at common magnification (500X). The surface roughness was also evaluated by a surface roughness tester. The descriptive statistic was evaluated the mean and standard deviation of surface roughness and Medcale T-Test was to test the mean difference of the surface roughness in each brands. This study showed an average grain size of 2-8 μm for each NiTi archwire. The wire surface of Ormco and Highland showed straiations along the longitudinal axes, however Sentalloy and NIC showed small pores on the wire surface. The surface roughness was 0.09 μm for Highland, 0.25 μm for Sentalloy, 0.28 μm for Ormco and 0.46 μm for NIC archwire. The Highland was smoothest and NIC was the roughest. There were in significant (p < 0.05) difference of surface roughness of each brands. The results showed that the four manufactures NiTi archwires were different in grain size, wire surface and surface roughness. During clinical application, these archwires may exhibit different mechanical properties, such as strength, hardness, ductity, and friction because of their microstructure.

Microstructural Control of 7075 Al Wrought Alloys through Thixoextrusion Route

2006 ◽  
Vol 510-511 ◽  
pp. 362-365 ◽  
Author(s):  
Young Ok Yoon ◽  
Hyung Ho Jo ◽  
Jin Kyu Lee ◽  
Dong In Jang ◽  
Shae K. Kim
Keyword(s):  
Grain Size ◽  
Liquid Fraction ◽  
Isothermal Holding ◽  
High Strength ◽  
Industrial Applications ◽  
High Productivity ◽  
Die Life ◽  
Average Grain Size ◽  
Low Energy Consumption ◽  
Holding Temperature

Thixoextrusion, one of the thixoforming processes, has advantages of high productivity, reduction of the extrusion pressure, extension of the die life, and cost saving owing to its low energy consumption compared with the conventional extrusion processes. Especially, thixoextrusion process is expected to be very effective for hard-to-form materials with high strength. The present study focuses on 7075 Al wrought alloy to investigate the potential industrial applications of the thixoextrusion process. The microstructural evolution of 7075 Al wrought alloy for thixoextrusion was investigated with respect to isothermal holding temperature and time in the partially remelted semisolid state. The results showed that the liquid fraction increased with increasing isothermal holding temperature and time while the average grain size was inversely proportional to isothermal holding temperature and time up to 5min. However, there was no big change of liquid fraction and average grain size with respect to isothermal holding temperature and time. The important fact that the liquid fraction and average grain size were almost uniform after 5 min holding time is considered very useful for thixoextrusion in terms of process control.

Effect of Warm Rolling on Microstructure and High Temperature Mechanical Behavior of a Nano-Structured Al-8Fe-2Mo-2V-1Zr Alloy

2005 ◽  
Vol 486-487 ◽  
pp. 411-414 ◽  
Author(s):  
Won Yong Kim ◽  
Jae Sung Park ◽  
Mok Soon Kim
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Elevated Temperatures ◽  
Hot Extrusion ◽  
Warm Rolling ◽  
Spray Forming ◽  
Grain Structure ◽  
Average Grain Size ◽  
Two Samples ◽  
Additional Process

Mechanical properties of a nano-structured Al-8Fe-2Mo-2V-1Zr alloy produced by spray forming and subsequent hot-extrusion at 420°C were investigated in terms of tensile test as a function of temperature. Warm rolling was adapted as an additional process to expect further refinement in microstructure. Well-defined equiaxed grain structure and finely distributed dispersoids with nano-scale in particle size were observed in the spray formed and hot extruded sample (as-received sample). The average grain size and particle size were measured to 500 nm and 50 nm, respectively. While it was found that warm rolling gives rise to precipitate fine dispersoids less than 10 nm without influencing the grain size of matrix phase, in the temperature range of RT∼150°C, distinguishable changes in ultimate tensile strength were not found between the as-received and warm-rolled samples. At elevated temperatures ranging from 350 to 550°C, warm-rolled sample showed a higher value of elongation than as-received one although similar values of elongation were observed between two samples at temperatures lower than 350°C.

scholarly journals Evaluation of Cryogenic Mechanical Properties of Resistance Seam-Welded Invar Alloy Sheet by Instrumented Indentation Test

2020 ◽  
Vol 8 (12) ◽  
pp. 1009
Author(s):  
Seunghun Choi ◽  
Jongho Won ◽  
Jung-Jun Lee ◽  
Hee-Keun Lee ◽  
Seong-Min Kim ◽  
...  
Keyword(s):  
Grain Size ◽  
Plastic Zone ◽  
Base Material ◽  
Indentation Test ◽  
Welding Current ◽  
Optical Microscope ◽  
Alloy Sheet ◽  
Invar Alloy ◽  
Instrumented Indentation ◽  
Average Grain Size

Invar alloy sheet was welded by resistance seam welding (RSW) with a constant electrode force and three different welding currents. Tensile properties were evaluated using instrumented indentation testing (IIT) with a spherical indenter and microstructure observations were obtained under an optical microscope. IIT performed on the base material at room temperature (RT) and −163 °C, a cryogenic temperature (CT), gave results in good agreement with those of tensile testing. The strength of each zone was higher in the order of heat-affected zone (HAZ) < weld nugget (WN) < base material (BM) because the amount of cold working was least in the BM, heavy metal elements and carbon vaporized during melting, and the WN was formed more tightly than the HAZ, effectively constraining the plastic zone generated by the indentation. As for the welding current, the nugget, which becomes larger and tighter as the current increases, more effectively constrained the plastic zone in the indentation, and this soon increased the strength. Generally, Invar is known to consist of single-phase austenite, and microstructure observations have confirmed that the average grain size is ordered as BM < HAZ < WN. Fan-like columnar grains developed in the direction of the temperature gradient, and equiaxed grains were observed near the BM. It was confirmed that the grain size in the WN also increases as the current is increased. Interestingly, the constraint effect with increasing nugget size was more important for strength than the grain size.

Effect of rate controlled sintering on microstructure and electrical properties of ZnO doped with bismuth and antimony oxides

1997 ◽  
Vol 12 (9) ◽  
pp. 2447-2454 ◽  
Author(s):  
Gaurav Agarwal ◽  
Robert F. Speyer
Keyword(s):  
Grain Size ◽  
Liquid Phase ◽  
Grain Growth ◽  
Elevated Temperatures ◽  
Antimony Oxide ◽  
Second Phase ◽  
Dopant Content ◽  
Average Grain Size ◽  
Rate Controlled ◽  
Grain Boundary Pinning

Various rate controlled sintering (RCS) schedules were used on isostatically pressed particulate compacts of ZnO with Bi2O3 and Sb2O3 additives. For low additive content, smaller average grain sizes with more rapid RCS schedules were attributable to thermal schedules which minimized the time at elevated temperatures where grain growth could occur. β–Bi2O3, Zn7Sb2O12, and Zn2Sb3Bi3O14 phases formed during/after sintering. Elevated heat-treatment temperatures favored the formation of Zn7Sb2O12 and additional β–Bi2O3, while Zn2Sb3Bi3O14 was dominant in sintered samples where the RCS schedule did not result in temperatures in excess of 1100 °C. Zn2Sb3Bi3O14 precipitated during sintering, functioning as grain boundary pinning sites which impeded ZnO grain growth. Bismuth and antimony oxide-based liquid facilitated sintering at lower temperatures, which in turn resulted in decreased average grain size. Rapid RCS schedules for samples with low dopant content resulted in lower sintering temperatures, since time was not allowed for Zn2Sb3Bi3O14 precipitation to deplete the liquid phase. For higher dopant contents, liquid phase was adequately plentiful, wherein longer RCS schedules resulted in lower sintering temperatures. Increasing concentration of second phase generally fostered decreased grain size and attenuated the effect of thermal schedule on the microstructure. Electrical resistance and breakdown voltage increased consistent with decreasing ZnO average grain size.

Effects of Specimen Diameter on Microstructure and Microhardness of Hot Extruded AZ31B Magnesium Alloy

2014 ◽  
Vol 1004-1005 ◽  
pp. 158-162 ◽  
Author(s):  
Xiang Ting Hong ◽  
Fu Chen ◽  
Fei Chen ◽  
Wang Yu ◽  
Bo Rong Sang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Size Effects ◽  
Strain Distribution ◽  
Elevated Temperatures ◽  
Az31b Magnesium Alloy ◽  
Specimen Diameter ◽  
Average Grain Size ◽  
Micro Parts

Microstructures of metal micro parts after microforming at elevated temperatures must be evaluated due to mechanical properties depend on average grain size. In this work, the effects of specimen diameter on the microstructure and microhardness of a hot-extruded AZ31B magnesium alloy were studied. Obvious size effect on microstructure and microhardness of the alloy could be observed. The size effects could be explained by strain distribution and dislocation density differences between the two kinds of specimens.

Annealing Treatment for Superplastic Forming of Twin Roll Casted AZ31 Magnesium Sheet

2011 ◽  
Vol 239-242 ◽  
pp. 50-54 ◽  
Author(s):  
Guo Dong Shi ◽  
Jun Qiao
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Mechanical Test ◽  
Dynamic Balance ◽  
Annealing Treatment ◽  
Optical Microscope ◽  
Grain Structure ◽  
Average Grain Size ◽  
Az31 Sheet ◽  
Twin Roll

Annealing treatments at 200°C, 250 °C, 300°C, and 350°C were conducted on a twin-roll casted AZ31 sheet with an initial average grain size of 10.11 mm. Microstructure and mechanical behaviors were studied by optical microscope observation and tensile mechanical test. Expermeintal results show that grain size experienced three stage evolution during 180 min annealing at each temperature: recrystallization refinement, stabilization under dynamic balance of recrystallization and grain growth, and grain growth. The minimum average grain size of 5.96 μm was achieved after 120 min annealing at 200°C. The refined grain structure causes a decrease of ultimate tensile strength and an increase of elongation, and facilitates superplastic deformation of the material.

Influence of Grain Size on Mechanical Properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP Steel

2011 ◽  
Vol 197-198 ◽  
pp. 655-661
Author(s):  
Ze Bin Yang ◽  
Ding Yi Zhu ◽  
Wei Fa Yi ◽  
Shu Mei Lin ◽  
Cheng Mei Du
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Strain Hardening ◽  
Twip Steel ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Microstructure Observation ◽  
Transmission Electron ◽  
Average Grain Size

We investigate the influence of grain size on mechanical properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP steel by unidirectional tensile. Meanwhile the microstructures of the TWIP steel were observed and analyzed by optical microscope (OM) and transmission electron microscope (TEM). The experimental results show that the TWIP steel’s yield strength and tensile strength decrease with the increasing of grain size, whereas the plasticity increases with it. When the average grain size reaches to 27μm, the tensile strength is 1080MPa, the elongation percentage is 77%, and the strength-plasticity product achieves the 83160MPa•%. Steel’s strain hardening rate can be changed from three-stage to four-stage with the increasing of grain sizes, the areas of strain hardening by twin deformation mechanism are expanded. Through the microstructure observation we found that, coarse-grained TWIP steel conducts to twinning formation, the high density twins can increase the alloy’s ductility by splitting the grain.

On Phenomenon of Superplasticity in Fe3AL with Large Grains

1994 ◽  
Vol 364 ◽  
Author(s):  
Aidang Shan ◽  
Dongliang Lin
Keyword(s):  
Tensile Test ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Initial Strain Rate ◽  
Optical Microscope ◽  
Al Alloys ◽  
Initial Strain ◽  
Atomic Percent ◽  
Maximum Elongation ◽  
Grain Sizes

AbstractA variety of Fe3Al alloys including Fe-25Al, Fe-28Al, Fe-28Al-4Cr and Fe-28Al-2Ti (all in atomic percent) have been investigated by tensile test to find if these alloys could have superplasticity at elevated temperatures, the results revealed that all these alloys exhibited large elongations when the temperature is higher than 600°C. At 850°C , under appropriate initial strain rate, the elongation is all above 300%. For Fe-28Al-2Ti, the maximum elongation reached 585%. Maximum m values are all above 0.3. Initial grain sizes are bigger than 100μm but became finer after deformation. Fracture happened with necking but no cavities were found under optical microscope. Characteristics of this phenomenon were summarized and discussed.

Influence of Annealing Time on Microstructure of Ni-W Alloys

2013 ◽  
Vol 747-748 ◽  
pp. 613-618
Author(s):  
Qiao Zhang ◽  
Shu Hua Liang ◽  
Chen Zhang ◽  
Jun Tao Zou
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Grain Size ◽  
Grain Boundaries ◽  
Annealing Time ◽  
Single Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size ◽  
Scanning Electron

The as-cast Ni-W alloys with 15wt%W, 25wt%W and 30wt%W were annealed in hydrogen at 1100. The effect of the annealing time on the microstructure of Ni-W alloys was studied, and the phase constituents and microstructure of annealed Ni-W alloys were characterized by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that no any phase changed for Ni-15%W, Ni-25%W and Ni-30%W alloys annealed for 60 min, 90 min and 150 min, which were still consisted of single-phase Ni (W) solid solution. However, microstructure had a significant change after annealing. With increase of annealing time, the microstructure of Ni-15%W alloy became more uniform after annealing for 90 min, and the average grain size was 95μm, whereas the grain size of Ni-15%W alloy increased significantly after annealing for 150 min. For Ni-25%W and Ni-30%W, there was no obvious change on the grain size with increase of annealing time, and the amount of oxides at grain boundaries gradually reduced. After annealing for 150 min, the impurities at grain boundaries almost disappeared. Subsequently, the annealing at 1100 for 150 min was beneficial for the desired microstructure of Ni-25%W and Ni-30%W alloys.

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