scholarly journals Evolution of Secondary α Phase during Aging Treatment in Novel near β Ti-6Mo-5V-3Al-2Fe Alloy

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2283 ◽  
Author(s):  
Haoyu Zhang ◽  
Chuan Wang ◽  
Siqian Zhang ◽  
Ge Zhou ◽  
Lijia Chen

Evolution of secondary α phase during aging treatment of a novel near β titanium alloy Ti-6Mo-5V-3Al-2Fe(wt.%) was studied by OM, SEM, and TEM. Results indicated that size and distribution of secondary α phase were strongly affected by aging temperature and time. Athermal ω phase formed after super-transus solution treatment followed by water quenching, and promoted nucleation of needle-like intragranular α in subsequent aging process. When aged at 480 °C, fine scaled intragranular α with small inter-particle spacing precipitated within β grains and high ultimate tensile strength above 1500 MPa was achieved. When the aging temperature increased, the size and inter-particle spacing of intragranular α increased and made the strength reduce, but the ductility got improved. When aging temperature reached as high as 600 °C, ω phase disappeared and intragranular α coarsened obviously, resulting in serious decrease of strength. While mutually parallel Widmanstätten α laths formed at the vicinity of β grain boundaries and grew into the internal area of β grains, and significant improvement of ductility was achieved. As the aging time increased from 4 h to 16 h at 600 °C, the intragranular α grew slightly and brought about minor change of mechanical properties.

Author(s):  
Seyed Mahmoud Ghalehbandi ◽  
Alireza Fallahi Arezoodar ◽  
Hossein Hosseini-Toudeshky

Effect of aging treatment on mechanical properties of an age-hardenable aluminum alloy after equal channel angular pressing at room temperature has been investigated using hardness, stress–strain behavior and surface fractography. Aluminum alloy 7075 was pressed after solution treatment. Yield stress, ultimate stress and hardness of pressed samples have increased significantly compared with those of coarse grain, but the elongation to failure has decreased. Also the pressed specimens were subjected to aging treatment at room temperature and temperatures of 80 °C, 100 °C, 120 °C and 140 °C to obtain the optimized strength and ductility. The results indicated that post–equal channel angular pressing aging at 80 °C has resulted in the maximum strength, and natural aging has resulted in good ductility and acceptable strength. It confirmed the fact that there is a potential in obtaining high strength and good ductility in age-hardenable alloys employing severe plastic deformation and subsequent aging.


2018 ◽  
Vol 929 ◽  
pp. 42-49
Author(s):  
Zuldesmi Mansjur ◽  
Hendro Maxwel Sumual

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.


2014 ◽  
Vol 783-786 ◽  
pp. 2423-2428 ◽  
Author(s):  
Hideki Hosoda ◽  
Kenta Kasuya ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
Shuichi Miyazaki

In order to develop new β (bcc) Ti alloys, the Ti-Fe-Sn system was focused and phase constitution, microstructure, mechanical properties of Ti-5mol%Fe-6mol%Sn and Ti-6mol%Fe-3mol%Sn were clarified in addition to aging effect. It was estimated by differential scanning calorimetry (DSC) that α phase is formed at temperature from 773-779K and that β transus temperature is 1019K in both the alloys. X-ray diffraction analysis revealed that, in both alloys, β single phase is formed after the solution treatment (ST) at 1273K followed by water quenching, while α phase is formed after the aging at 773K and 873K for 3.6ks. The formation of α phase is also confirmed by optical microscopy. The volume fraction of α phase reaches to 90% in Ti-5Fe-6Sn and 80% in Ti-6Fe-3Sn after the aging at 873K for 3.6ks. The 0.2% proof stress was increased by aging at 873K from 550MPa to 650MPa in Ti-5Fe-6Sn and 500MPa to 690MPa in Ti-6Fe-3Sn. Besides, apparent Young’s modulus measured by dynamic mechanical analysis was raised by the aging treatment. These changes in the mechanical properties were discussed in connection with α phase precipitation.


2020 ◽  
Vol 39 (1) ◽  
pp. 501-509
Author(s):  
Wan-Liang Zhang ◽  
Wen-Tao Hao ◽  
Wei Xiong ◽  
Guo-Zheng Quan ◽  
Jiang Zhao ◽  
...  

AbstractThe solution-aging treatment parameters, including solution temperature, cooling rate and aging temperature, have significant influences on the microstructures and comprehensive mechanical properties of titanium alloy. In this work, the detailed microevolution behaviors of Ti–10V–2Fe–3Al alloy under different solution and aging conditions have been investigated through a series of heat-treatment experiments. The results of solution-treatment experiments reveal that the content of αp-phase is reduced to zero as the solution temperature is raised to a certain α → β critical transformation point. Recrystallized β-grains can be observed at the solution temperature of 820°C. In addition, the cooling way (air cooling or water cooling) has little influence on the microevolution behaviors for this alloy during the solution-treatment process. As for the solution-aging-treatment experiments, the results reveal that αs-phases are precipitated from the supersaturated β-phase, and the fraction of αs-phase increases with increasing aging temperature. However, the precipitated α-grains intend to coalesce and coarsen as the aging temperature raises above 510°C. Therefore, the advocated solution-aging-treatment program is solution treatment at 820°C with air cooling followed by aging treatment at 510°C with air cooling.


Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1274
Author(s):  
Ricardo Carabes ◽  
Héctor Carreón ◽  
Maria L. Carreon ◽  
Melchor Salazar ◽  
Pedro Hernández

The article reports a study carried out on metallic samples extracted from a metallurgically bonded clad pipe (API 5L X65 steel-Inconel 825 alloy) subjected to a solution heat treatment at 1200 °C and a subsequent aging treatment at 650 °C for different times in order to promote microstructural changes in thermo-metallurgical bonded materials. The non-destructive thermoelectric potential (TEP) technique was used to monitor microstructure changes due to the artificial aging process. In addition, micro-hardness tests were carried out on the metallic materials and micrographs were obtained by means of an optical and scanning electron microscope (SEM). The TEP value changed with solution treatment temperature and reached a maximum value for solution treatment at 1200 °C. The changes in TEP during solution treatment were caused by changes in the solubility of the alloying elements. In the artificial aging process, the TEP value decreased with increasing aging time due to the precipitation process, but exhibited distinct characteristics for the different zones at the clad pipe samples.


2007 ◽  
Vol 561-565 ◽  
pp. 2067-2070 ◽  
Author(s):  
Tatsuaki Sakamoto ◽  
Kiyomichi Nakai ◽  
Munehiro Maeda ◽  
Sengo Kobayashi

Microstructure evolutions and hardness variation during aging in metastable β titanium alloy TIMETAL®LCB have been examined. In as-quenched specimen after solution treatment, athermal ω phase formed. Isothermal ω phase formed during aging at 623 K, and α phase formed after precipitation of isothermal ω phase during aging at 673 and 773 K. Alpha phase nucleated at isothermal ω phase, and had the orientation relationship with β and ω, (111)β//(0001)ω//(1120 )α and [10 1 ]β//[1120 ]ω//[0001]α . During aging at 873 K, α phase formed without isothermal ω phase. Hardness increased with increasing aging time and decreasing aging temperature, partly because number density of isothermal ω or α precipitates increased with increasing aging time and decreasing aging temperature.


2020 ◽  
Vol 321 ◽  
pp. 11032
Author(s):  
Jingzhe Niu ◽  
Yulei Gub ◽  
Yanhua Guo ◽  
Wenjun Wuc ◽  
Cong Wu ◽  
...  

This work presents a comprehensive study on the microstructure evolution and mechanical property under different heat treatment procedures of a new near β type titanium Ti-5321(Ti-5Al-3Mo-3V-2Cr-2Zr-1Nb-1Fe). Two solution temperatures(830°C and 900°C) and a group of aging temperatures(300-650°C) were carried out to investigate the influence of heat treatment on this new alloy. The strengthening mechanism of Ti-5321 after solution and aging treatment was discussed by analyzing the microstructure and its mechanical properties. The best ultimate tensile strength can be achieved to 1564 MPa with 5% on elongation when solution treated at 830°C and aging at 450°C for this new alloy. The lamellar and globular α grains can be found in all 830°C solution treated specimens which contribute to a better ductility. Ultra-fine α phase can be found in all low aging temperature treated specimens but will coarsen significantly when raising the aging temperature and thus increase the tensile strength and lower the ductility. All these results can provide a comprehensive guidance on heat treatment for this new near β type titanium in the future.


2013 ◽  
Vol 747-748 ◽  
pp. 932-936 ◽  
Author(s):  
Xin Nan Wang ◽  
Yue Fei ◽  
Xiao Hu Zhou ◽  
Zhi Shou Zhu ◽  
Jun Li ◽  
...  

The evolution regularities of microstructure and property of a new metastable β titanium alloy with different solution treatment and aging treatment were studied using optical microscope (OM), scanning electron microscopy (SEM) and tensile test. The results show that, the volume fraction of primary α phase decreases and globularization of α phase occurs with the increasing aging temperature from 540 to 580 and solution treated temperature from 800 to 820. When the solution treated temperature is 820, the acicular secondary α phase precipitates along β grain boundary. The strength of the investigated alloy increases and the ductility decreases with the solution treated temperature increasing. While the strength of the investigated alloy increases and the ductility decreases with the aging temperature decreasing.


2014 ◽  
Vol 794-796 ◽  
pp. 851-856
Author(s):  
Tadashiege Nagae ◽  
Nobuhiro Tsuji ◽  
Daisuke Terada

Accumulative roll-bonding (ARB) process is one of the severe plastic deformation processes for fabricating ultrafine grained materials that exhibit high strength. In aluminum alloys, aging heat treatment has been an important process for hardening materials. In order to achieve good mechanical properties through the combination of grain refinement hardening and precipitation hardening, an Al-4.2wt%Ag binary alloy was used in the present study. After a solution treatment at 550°C for 1.5hr, the alloy was severely deformed by the ARB process at room temperature (RT) up to 6 cycles (equivalent strain of 4.8). The specimens ARB-processed by various cycles (various strains) were subsequently aged at 100, 150, 200, 250°C, and RT. The hardness of the solution treated (ST) specimen increased by aging. On the other hand, hardness of the ARB processed specimen decreased after aging at high temperatures such as 250°C. This was probably due to coarsening of precipitates or/and matrix grains. The specimen aged at lower temperature showed higher hardness. The maximum harnesses achieved by aging for the ST specimen, the specimens ARB processed by 2 cycles, 4 cycles and 6 cycles were 55HV, 71HV, 69HV and 65HV, respectively. By tensile tests it was shown that the strength increased by the ARB process though the elongation decreased significantly. However, it was found that the tensile elongation of the ARB processed specimens was improved by aging without sacrificing the strength. The results suggest that the Al-Ag alloy having large elongation as well as high strength can be realized by the combination of the ARB process for grain refinement and the subsequent aging for precipitation hardening.


2005 ◽  
Vol 475-479 ◽  
pp. 317-320 ◽  
Author(s):  
Jing Pei Xie ◽  
Ji Wen Li ◽  
Zhong Xia Liu ◽  
Ai Qin Wang ◽  
Yong Gang Weng ◽  
...  

The in-situ Ti alloying of aluminium alloys was fulfilled by electrolysis, and the material was made into A356 alloy and used in automobile wheels. The results show that the grains of the A356 alloy was refined and the second dendrites arm was shortened due to the in-situ Ti alloying. Trough 3-hour solution treatment and 2-hour aging treatment for the A356 alloy, the microstructures were homogeneous, and Si particles were spheroid and distribute in the matrix fully. The outstanding mechanical properties with tensile strength (σb≥300Mpa) and elongation values (δ≥10%) have been obtained because the heat treatment was optimized. Compared with the traditional materials, tensile strength and elongation were increased by 7.6~14.1% and 7.4~44.3% respectively. The qualities of the automobile wheels were improved remarkably.


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