scholarly journals Extremely rapid age hardening behavior in solution treated Ti-5Al-2Fe-3Mo

2020 ◽  
Vol 321 ◽  
pp. 11016
Author(s):  
Tomonori KUNIEDA ◽  
Hideki FUJII ◽  
Kazuhiro TAKAHASHIa
Keyword(s):  
Phase Transformation ◽  
Vickers Hardness ◽  
Martensite Transformation ◽  
Solution Treatment ◽  
Age Hardening ◽  
Time Dependency ◽  
Β Phase ◽  
Eds Analysis ◽  
Solution Treated ◽  
Initial Stage

To grasp age hardening and phase transformation behaviors in a β rich α+β type titanium alloy, Ti-5Al-2Fe-3Mo, during aging at 300-500°C after the solution treatment at high α+β temperature. Vickers hardness and microstructure changes during aging were closely investigated using XDR and TEM/EDS. Vickers hardness rapidly increased with increasing holding time and reached about 440HV by aging at 450°C for only 5 min. It further increased to 510HV in 8h of aging time. The initial stage of age hardening is extremely fast compared to that in other conventional α+β and β type titanium alloys. After aging for only 5min, extremely fine acicular products of about 2 to 10 nm in width were formed in the transformed β phase. TEM/EDS analysis revealed that all substitutional alloying elements, Al, Fe and Mo, homogeneously distributed after the aging, indicating that the transformation is diffusionless as far as substitutional elements are concerned just like martensite transformation although it has time dependency. To explain the mechanism of this unique phase transformation having features of isothermal martensite transformation, we propose bainitic transformation where interstitials such as O diffuse without conspicuous diffusion of substitutional elements.

Effect of Quenching and Reheating on Isothermal Phase Transformation in Ti-15Nb-10Zr Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 582-587 ◽  
Author(s):  
Sengo Kobayashi ◽  
Ryoichi Ohshima ◽  
Kiyomichi Nakai ◽  
Tatsuaki Sakamoto
Keyword(s):  
Phase Transformation ◽  
Solution Treatment ◽  
The Other ◽  
Matrix Microstructure ◽  
Iced Brine ◽  
Β Phase ◽  
Solution Treated ◽  
Α Phase ◽  
Other Hand ◽  
Means Of Transmission

Isothermal phase transformation in Ti-15Nb-10Zr (at%) alloys has been examined by mainly means of transmission electron microscopy. Specimens solution-treated at 1000°C in  phase field were directly held at temperatures between 350 and 450°C for 1.8-86.4ks, which are called "DH (direct holding)-specimen". On the other hand, some specimens solution-treated at 1000°C were quenched into iced brine and then aged at temperatures between 350 and 450°C, which are called "QA(quench and aging)-specimen". In the DH-specimen held at 400°C α phase formed in β matrix. Microstructure evolution of QA-specimen aged at 400°C, on the other hand, is as follows.  phase formed in β matrix after aging for 1.8ks and further aging led to growth of  phase. After prolonged aging, α phase started to form in β matrix. These experimental results indicate that process of the quenching and reheating promotes the formation of  phase. Specimen quenched into iced brine after solution treatment exhibited α'' phase formation. The α'' phase in the quenched specimen would transform into β phase during reheating to the aging temperature. Reversion process of α''  β phase could promote the formation of  phase in β. Microstructure formation in the DH- and QA-specimens at 350 and 450°C will also be explained.

Effect of Solution Treatment on Microstructures and Hardness of Mg-Gd-Y-Zr Alloy

2014 ◽  
Vol 937 ◽  
pp. 182-186
Author(s):  
Quan An Li ◽  
Lei Lei Chen ◽  
Wen Chuang Liu ◽  
Xing Yuan Zhang ◽  
Hui Zhen Jiang
Keyword(s):  
Vickers Hardness ◽  
Cast Alloy ◽  
Solution Treatment ◽  
Hardness Measurement ◽  
Solution Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solution Treated ◽  
Primary Particles ◽  
Zr Alloy

The influence of the solution treatment (at the temperature of 500-520°C for 4-12 h) on microstructures and mechanical properties of Mg-Gd-Y-Zr alloy was investigated by means of optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Vickers hardness measurement. The as-cast alloy contains a microstructure consisting of α-Mg matrix, Mg5Gd phase and Mg24Y5phase. With increasing solution temperature and time, the quantity of the primary particles (Mg5Gd and Mg24Y5) in the alloy continually decreased, and the degree of recrystallization gradually increased, which result in the gradual decrease of the Vickers hardness of the solution-treated alloys.

Effects of T6 Age Hardening on Microstructure and Mechanical Properties of Al-Si-Cu Cast Aluminium Alloy

2013 ◽  
Vol 770 ◽  
pp. 88-91
Author(s):  
Amporn Wiengmoon ◽  
Pattama Apichai ◽  
John T.H. Pearce ◽  
Torranin Chairuangsri
Keyword(s):  
Electron Microscopy ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Aging Time ◽  
Artificial Aging ◽  
Solution Treatment ◽  
Hot Water ◽  
Age Hardening ◽  
Solution Treated ◽  
Cast Condition

Effects of T6 artificial aging heat treatment on microstructure, microhardness and ultimate tensile strength of Al-4.93 wt% Si-3.47 wt% Cu alloy were investigated. The T6 age hardening treatment consists of solution treatment at 500±5°C for 8 hours followed by quenching into hot water at 80°C and artificial aging at 150, 170, 200 and 230°C for 1-48 hours followed by quenching into hot water. Microstructure was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). XRD and SEM revealed that the microstructure in the as-cast condition consists of primary dendritic α-Al, acicular-plate and globular forms of eutectic Si and intermetallic phases including globular Al2Cu and a flake-shape Al5FeSi. By T6 aging hardening, some intermetallics were dissolved and spheroidized. The volume fraction of eutectic phases in the as-cast, solution-treated, and solution-treated plus aging at 170°C for 24 hours is 17%, 12% and 10%, respectively. TEM results showed that precipitates in under-aging condition at 170° C for 6 hours are in the form of disc shape with the diameter in the range of 7-20 nm. At peak aging at 170°C for 24 hours, thin-plate precipitates with about 3-10 nm in thickness and 20-100 nm in length were found, lengthening to about 30-200 nm at longer aging time. The microhardness and ultimate tensile strength were increased from 71 HV0.05 and 227 MPa in the as-cast condition up to 140 HV0.05 and 400 MPa after solution treatment plus aging at 170°C for 24 hours, and decreased at prolong aging time.

Microstructural Change of β′ Phase and Hardness Change in As-Solutionized Dental Ag-20Pd-12Au-14.5Cu Alloy

2012 ◽  
Vol 508 ◽  
pp. 166-171
Author(s):  
Yong Hwan Kim ◽  
Mitsuo Niinomi ◽  
Junko Hieda ◽  
Masaaki Nakai ◽  
Hisao Fukui
Keyword(s):  
Vickers Hardness ◽  
Treatment Time ◽  
Solution Treatment ◽  
Microstructural Change ◽  
Β Phase ◽  
Distribution Of Elements ◽  
Hardness Change

Change in the Microstructure of the L10-Type Ordered β' Phase Precipitated in Ag-20Pd-12Au-14.5Cu Alloy (mass%) Subjected to Solution Treatment with Varying Solution Treatment Time Was Investigated. The Size of the β' Phase Is Found to Decrease with Increasing Solution Treatment Time and the Vickers Hardness of the Alloy after Solution Treatment Decreases. Experimental Observations Show that the Microstructural Change of the β' Phase Strongly Contributes to the Change in Vickers Hardness. In Addition, the Formation and Growth of the β' Phase Are Concluded to Be Affected by the Distribution of Elements through Solution Treatment.

TEM Study for Strengthening Mechanisms in Elgiloy

2010 ◽  
Vol 442 ◽  
pp. 268-274 ◽  
Author(s):  
I.N. Qureshi ◽  
S. Rani ◽  
F. Yasmin ◽  
M. Farooque
Keyword(s):  
Electron Microscope ◽  
Cold Work ◽  
Cold Deformation ◽  
Solution Treatment ◽  
Optical Microscope ◽  
Age Hardening ◽  
Solution Treated ◽  
Transmission Electron ◽  
P Transformation ◽  
Cold Worked

Elgiloy is Co based alloy (40wt%Co, 20wt%Cr, 15wt%Ni, 14wt%Fe and 7wt%Mo). It was strengthened by cold work and is capable of additional hardening by aging. The effects of solution treatment, cold working and age-hardening on the microstructure of elgiloy were investigated using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). As rolled strips were solution treated at 1065°C/1hr. These solution treated strips were then reduced 50% by cold rolling. After cold-deformation both є-hcp phase and fcc deformation twins are also considered to coexist at room temperature. The cold worked strips were then age hardened at (450-600)°C. The age hardened strips showed formation of additional є-phase (via α f c c є h c p transformation).

scholarly journals Influence of Solution Treatment Time on Precipitation Behavior and Mechanical Properties of Mg-2.0Nd-2.0Sm-0.4Zn-0.4Zr Alloy

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5037
Author(s):  
Tao Ma ◽  
Sicong Zhao ◽  
Liping Wang ◽  
Zhiwei Wang ◽  
Erjun Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Treatment Time ◽  
Solution Treatment ◽  
Basal Plate ◽  
Aged Alloy ◽  
Precipitation Behavior ◽  
Β Phase ◽  
Solution Treated ◽  
Strengthening Phases

The effect of solution treatment time on the microstructure and mechanical properties of aged the Mg-2.0Nd-2.0Sm-0.4Zn-0.4Zr (wt.%) alloy were investigated to give full play to the performance of the alloy. As the solution treatment time increased from 2 h to 12 h at 788 K, the grain size of the solution-treated alloy significantly increased, and the network-like β-Mg12(Nd, Sm, Zn) phase gradually dissolved into the α-Mg matrix. It should be noted that no obvious residual β phase can be observed when the solution treatment time was more than 8 h. After the solution-treated alloy was further aged at 473 K for 18 h, a large number of nanoscale precipitates were observed in the α-Mg matrix. The solution treatment time was 2 h, the α-Mg matrix mainly consisted of spherical-shaped and basal plate-shaped precipitates. Upon the increase of solution treatment time to 8 h, the key strengthening phases transformed from spherical-shaped precipitates and basal plate-shaped precipitates to prismatic plate-shaped β′ precipitates. The orientation relationship between β′ precipitates and α-Mg matrix was (1¯10)β′ // (11¯00)α and [112]β′ // the [224¯3]α. Further increasing of solution treatment time from 8 h to 12 h, the key strengthening phases mainly were still β′ precipitates. The solution treatment of aged alloy was carried out at 788 K for 8 h, which achieved optimal ultimate tensile strength (UTS) of 261 ± 4.1 MPa, yield strength (YS) of 154 ± 1.5 MPa, and elongation of 5.8 ± 0.1%, respectively.

scholarly journals Effect of microstructure on Ti3Al precipitation during ageing of Ti-6Al-4V alloy

2020 ◽  
Vol 321 ◽  
pp. 12014
Author(s):  
B. Callegari ◽  
J. V. Marçola ◽  
K. Aristizabal ◽  
F. A. Soldera ◽  
F. Mücklich ◽  
...  
Keyword(s):  
Rietveld Refinement ◽  
Age Hardening ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Solution Treated ◽  
Effect Of Microstructure

The aim of the present work is to explore the age-hardening potential of Ti-6Al-4V (Ti-64) alloy with variation of the starting microstructure, with attention to the precipitation of nano-sized Ti3Al phase, as influenced by microstructural features. The alloy was either solution-treated or deformed by compression at temperatures above and below its β-transus to produce microstructures comprising martensitic, lamellar and globular α morphologies, as well as the existence or absence of β phase, and subsequently submitted to ageing treatments at 400°C/8h using in situ x-ray diffraction. Precipitated fractions of Ti3Al were obtained via Rietveld refinement and aged microstructures were characterized by micro-hardness measurements. Results show that α2 precipitation is favored by a globular morphology of α and hindered by a martensitic α morphology, and suggest that the presence of β phase also has as influence on precipitation.

Enhancement of Mechanical Properties of Cast Beta-Type Titanium Alloy by Aging Treatment

2018 ◽  
Vol 929 ◽  
pp. 42-49
Author(s):  
Zuldesmi Mansjur ◽  
Hendro Maxwel Sumual
Keyword(s):  
Mechanical Properties ◽  
Aging Time ◽  
Vickers Hardness ◽  
Aging Temperature ◽  
Dendritic Structure ◽  
Solution Treatment ◽  
Aging Treatment ◽  
High Oxygen Content ◽  
Precision Casting ◽  
Β Phase

Beta type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) is one of the titanium alloys which have gained much attention in dental applications. Dental precision casting is predominant for fabricating dental prostheses. However, there is a possibility for the mechanical properties of its casting to be degraded because of a α case, shrinkages and pores and a dendrite structure. One of the ways to enhance their mechanical properties is heat treatment process. Therefore, the aim of this study is to investigate the effect of aging treatment on mechanical properties and microstructure of TNTZ cast into magnesia based mold in order to improve its mechanical properties. As results, the Vickers hardness of the cast TNTZ after solution treatment is larger than that of the wrought TNTZ. The aging curve of the cast and the wrought TNTZ at an aging temperature of 673 K and 723 K exhibit almost similar pattern. For each aging time, the higher the aging temperature, the smaller the Vickers hardness for both alloys. Microstructures of cast TNTZ at various aging conditions consist of a dendritic structure and the average diameters of their grain size are around 40 μm. The diffraction peaks of precipitation of α and β phase s are detected in under aging (UA), peak aging (PA) and over aging (OA) conditions for both aging temperatures. However, the diffraction peak of ω phase is observed only in OA condition for cast TNTZ at aging temperature of 673 K. The highest tensile strength of the cast TNTZ and the wrought TNTZ at both aging temperatures are in PA condition and the elongation decrease continuously by increasing aging time. The tensile strengths of cast TNTZ in UA, PA and OA conditions at an aging temperature of 723 K are lower and their elongations are higher in comparison with those of 673 K. The high oxygen content seems to contribute to the poor elongation. SEM fractographs of the cast TNTZ at aging temperatures of 673 and 723 K in UA, PA and OA conditions show the brittle morphology with intergranular fracture that increases with increasing of aging time.

Fabrication of Ti-Sn-Cr Shape Memory Alloy by PM Process and its Properties

2012 ◽  
Vol 706-709 ◽  
pp. 1943-1947 ◽  
Author(s):  
Sumio Ashida ◽  
H. Kyogoku ◽  
Hideki Hosoda
Keyword(s):  
Shape Memory ◽  
Martensite Transformation ◽  
Sintering Temperature ◽  
Solution Treatment ◽  
Strain Curve ◽  
Aged Alloy ◽  
Sintered Alloy ◽  
Stress Strain Curve ◽  
Plateau Region ◽  
Solution Treated

Ti-Sn-Cr shape memory alloys were fabricated by the powder metallurgy (PM) process. The mixed powders in composition of Ti-3at%Sn-7at%Cr were prepared using a V-blender. The mixed powders were filled into a graphite die, and then sintered at a temperature between 1023 K and 1223 K using a pulse current sintering equipment. The sintered alloy was solution-treated and then aged. The phase structure and the tensile properties of the alloy obtained were investigated. The relative density of the as-sintered alloy increased with elevating sintering temperature, and the maximum relative density was 99.5 % at a sintering temperature of 1223 K. Although the as-sintered alloy was high density, the microstructure of the alloy was inhomogeneous. Thus it was found that the solution treatment was needed to obtain the homogeneous microstructure of the alloy. The alloy which is mainly consisted of the β phase was obtained by performing solution treatment. The plateau region due to the slip deformation was observed in the stress-strain curve of the solution treated alloy, but that due to the stress induced martensite transformation could not be done. The plateau region due to the stress induced martensite transformation, however, was appeared in the stress-strain curve of the aged alloy. This means that the aged alloy has shape memory properties. It was also found from the result of bending test that the alloy fabricated by the PM process has obviously shape recovery properties.

The Microstructure and Mechanical Properties of Heat Treated NiCr20TiAl Superalloy

2016 ◽  
Vol 849 ◽  
pp. 531-536
Author(s):  
Ran Wei ◽  
Hui Yun Wu ◽  
Qing Quan Zhang ◽  
Ming Yang Li ◽  
Yu Cao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vickers Hardness ◽  
Mechanical Performance ◽  
Cast Alloy ◽  
Energy Dispersive Spectrometer ◽  
Solution Treatment ◽  
Optical Microscope ◽  
Age Hardening ◽  
Nickel Base Superalloy ◽  
Microstructure And Mechanical Properties

NiCr20TiAl is a typical age-hardening superalloy with Ni-Cr as matrix and γ′ as strengthening phase. The microstructure and mechanical properties of nickel base superalloy NiCr20TiAl under different heat treatment were examined by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), optical microscope (OM) and mechanical tester. The results showed that superior comprehensive mechanical performance of NiCr20TiAl cast alloy was achieved by 1050°C/8h, air cool (AC) +700°C/16h, AC treatment. The edge cracks problem was resolved by 1150°C/1h, water quench (WQ) solid solution treatment before cold rolling process. The vickers hardness of the alloy decreases from 308 to 148. The vickers hardness of the NiCr20TiAl alloy could be controlled below 250 by 1080°C/2min treatment.

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