Influence of Substitution of Fe by Mo on Heat Treatment Behavior in Ti-Mo-Fe Alloys

2021 ◽  
Vol 1016 ◽  
pp. 162-169
Author(s):  
Kyosuke Mizuta ◽  
Shotaro Miyake ◽  
Masahiko Ikeda ◽  
Masato Ueda

In order to reduce the cost of β-type Ti alloys, the use of Fe as an alloying element has been studied. However, Fe is known to have a very high diffusion coefficient in β-Ti of about 2.6×10-12 m2/s at 1200 K, and its behavior during heat treatment is expected to be difficult to control. By contrast, Mo, which is also a β-stabilizing element, has a diffusion coefficient of only about 2.5×10-14 m2/s at 1200 K, i.e., roughly 100 times smaller than that of Fe1), 2). In this study, the effect of the partial substitution of Fe with Mo on the aging behavior of β-Ti alloys was investigated using X-ray diffraction, electric resistivity, and Vickers hardness measurements. Ti-Mo-Fe alloys were solution-treated by holding at 1173 K for 3.6 ks and then quenching in ice water. In the X-ray diffraction patterns for the resulting samples, only peaks associated with the β phase were identified. It was found that the electrical resistivity and Vickers hardness decreased with increasing Mo content. As the Mo-to-Fe ratio increased, the decrease in electrical resistivity and the increase in Vickers hardness occurred later during the isothermal aging process. This was due to a delay in isothermal ω-phase precipitation.

2016 ◽  
Vol 879 ◽  
pp. 119-124 ◽  
Author(s):  
Masahiko Ikeda ◽  
Masato Ueda

Titanium (Ti) exhibits many attractive properties that enable practical applications. It is also considered to be a ubiquitous element, since it has the ninth highest Clarke number among all the elements. However, the principal beta-stabilizing elements for Ti, molybdenum and vanadium, can be very expensive, and so many Ti alloys are also costly. For this reason, less expensive alloying elements would be preferable. Iron (Fe) and manganese (Mn) are beta stabilizers for Ti alloys that are readily available, since they have the fourth and eleventh highest Clarke numbers, respectively. Furthermore, since Fe has a large diffusion coefficient in the beta phase of Ti, precipitation of the omega phase occurs more quickly when Fe is added. The behaviors of Ti-Mn and Mn-Fe alloys during heat treatment have been investigated and it has been found that, in some alloys, the isothermal omega phase is precipitated. Because this phase can lead to brittleness of the alloy, it is very important to suppress its precipitation. Since it is well known that aluminum (Al) suppresses isothermal omega precipitation, the present work investigated the effects of Al content on the phase constitution and heat treatment behavior of Ti-8.5 mass%Mn-1 mass%Fe-0, 1.5, 3.0 and 4.5 mass%Al alloys using electrical resistivity, Vickers hardness, and X-ray diffraction measurements. In the case of each of these alloys, whether solution-treated or water-quenched, only the beta phase was identified. The resistivities at room and liquid nitrogen temperatures were found to increase monotonically with Al content, while the Vickers hardness decreased up to 3 mass% Al and then remained constant. The addition of Al was found to suppress omega precipitation.


2011 ◽  
Vol 172-174 ◽  
pp. 190-195 ◽  
Author(s):  
Giorgia T. Aleixo ◽  
Eder S.N. Lopes ◽  
Rodrigo Contieri ◽  
Alessandra Cremasco ◽  
Conrado Ramos Moreira Afonso ◽  
...  

Ti-based alloys present unique properties and hence, are employed in several industrial segments. Among Ti alloys, β type alloys form one of the most versatile classes of materials in relation to processing, microstructure and mechanical properties. It is well known that heat treatment of Ti alloys plays an important role in determining their microstructure and mechanical behavior. The aim of this work is to analyze microstructure and phases formed during cooling of β Ti-Nb-Sn alloy through different cooling rates. Initially, samples of Ti-Nb-Sn system were prepared through arc melting furnace. After, they were subjected to continuous cooling experiments to evaluate conditions for obtaining metastable phases. Microstructure analysis, differential scanning calorimetry and X-ray diffraction were performed in order to evaluate phase transformations. Depending on the cooling rate and composition, α” martensite, ω phase and β phase were obtained. Elastic modulus has been found to decrease as the amount of Sn was increased.


2003 ◽  
Vol 18 (1) ◽  
pp. 166-172 ◽  
Author(s):  
Kun'ichi Miyazawa ◽  
Minoru Akaishi ◽  
Yusuke Kuwasaki ◽  
Tadatomo Suga

Structural, mechanical, and electrical properties were examined for C60 whiskers, high-pressure sintered C60 whiskers, and C60 powder. A high density of dislocations was observed in the C60 whiskers, and the C60 whiskers with diameters of a few hundred nanometers were found to be flexible. Although both the specimens sintered under the same condition showed similar surface x-ray diffraction profiles with a strong accumulation of [110]tr orientation, the sintered C60 whiskers showed a higher micro-Vickers hardness and an electrical resistivity four orders of magnitude lower than that of the sintered C60 powder.


2007 ◽  
Vol 561-565 ◽  
pp. 1435-1440 ◽  
Author(s):  
Masahiko Ikeda ◽  
Tsuyoshi Miyazaki ◽  
Satoshi Doi ◽  
Michiharu Ogawa

Phase constitution in the solution-treated and quenched state and the heat treatment behavior were investigated by electrical resistivity, hardness, and elastic modulus measurements, X-ray diffraction, and optical microscopy. Hexagonal martensite and the β phase were identified in the Zr-5mass%Nb alloy. β and ω phases were identified in the Zr-10 and 15mass%Nb alloys, and only the β phase was identified in the Ti-20Nb alloy. Resistivity at RT, Vickers hardness and elastic modulus increased up to 10Nb and then decreased dramatically at 15Nb. Above 15Nb, these values slightly decreased. The elastic moduli for 15Nb and 20Nb were 59.5 and 55.5 GPa, respectively. On isochronal heat treatment, the isothermal ω phase precipitated between 473 and 623 K and then the α phase precipitated in the 10Nb, 15Nb and 20Nb alloys.


2008 ◽  
Vol 23 (4) ◽  
pp. 1020-1025 ◽  
Author(s):  
Young-Sam Jeon ◽  
Hyunho Shin ◽  
Young-Hyun Lee ◽  
Sang-Won Kang

A post heat treatment of reaction-sintered SiC at 1700 °C in nitrogen atmosphere significantly reduced electrical resistivity. A trace of insulating Si3N4 phase was detected via nitrogen heat treatment in high-resolution transmission electron microscopy observation; however, based on x-ray photoelectron spectroscopy, the evidence of nitrogen doping into SiC lattice has been claimed as the mechanism to the decreased resistivity. The increase of the total volume of SiC was apparent in x-ray diffraction during the nitrogen heat treatment, which was interpreted to stem from the growth of the nitrogen-doped intergranular SiC particles and surface doping of the primary SiC to reduce the contact resistance between the primary SiC particles.


2012 ◽  
Vol 581-582 ◽  
pp. 773-776
Author(s):  
Er Chao Ding ◽  
Zhen Yong Man ◽  
Xin Xin Yang ◽  
Jing Tai Zhao

The effects of heat treatment on microstructure and corrosion resistance of Ni-Cr-Mo-Fe nickel-based alloys were investigated by X-ray diffraction (XRD), metallographic microscope (MM), scanning electron microscopy (SEM) and electrochemical analysis, respectively. Experimental results indicated that the samples which were prepared via electric arc melting shielded by argon were pure solid solutions with homogeneous microstructure. Segregation of chromium element and slightly smaller grain size were found after heat treatment. Better corrosion resistance of samples was achieved after heat treatment, due to improvement of microstructure, morphology and distribution of elements.


2014 ◽  
Vol 783-786 ◽  
pp. 562-567 ◽  
Author(s):  
Masahiko Ikeda ◽  
Masato Ueda ◽  
Yoshinori Sumi ◽  
Mitsuo Niinomi

Titanium is considered to be a ubiquitous element since it has the 9th-highest Clarke number of all elements. Iron and manganese can also be used as beta stabilizers for Ti alloys, and can be considered to be ubiquitous because of their 4th- and 11th-highest Clarke numbers, respectively. However, investigations into the behavior of Ti-Mn-Fe alloys during heat treatment have shown that in some alloys, the isothermal omega phase is precipitated. Because this phase can lead to brittleness, it is very important to prevent it from forming. It is well known that aluminum can suppress the precipitation of the isothermal omega phase. Thus, in the present study, we investigated the effect of Al content on the phase constitution and heat-treatment behavior of Ti-8.5mass%Mn-1mass%Fe-0 to 4.5mass%Al alloys using electrical resistivity, Vickers hardness, and X-ray diffraction measurements. In all solution-treated and quenched alloys, only the beta phase was identified, thus confirming the suppression of omega-phase precipitation. The resistivity was found to increase monotonically with Al content, while the Vickers hardness decreased up to 3 mass% Al and then remained constant.


In this work, ZA-27 alloy was fabricated and solid solution treatment at 120, 240 and 360 °C for 1 hr., microstructure and physical properties of alloy were studied by X-ray diffraction, scanning electron microscopy. Results observed that the microstructure of ZA-27 alloy manufactured (as-cast) was composed of α, β, η and ε phases, then decomposed to β phase at 360 oC. The heat treatment of ZA-27 alloys influenced on microstructure, decreasing of strength and hardness, but also causes increasing of elongation. The wear rates of changes increase with increasing solid solution treatment


2002 ◽  
Vol 16 (20) ◽  
pp. 769-774
Author(s):  
S. SIMON ◽  
R. V. F. TURCU ◽  
M. POP ◽  
Gh. BORODI

The effect of bismuth partial substitution by lead, cadmium or tin on the properties of the polycrystalline systems Bi 2-x M x Sr 2 Ca 2 Cu 3 O z (M = Pb, Cd or Sn) was investigated. The samples were obtained from amorphous precursors by heat treatment applied in several stages. X-ray diffraction analysis and static susceptibility measurements were carried out in order to characterize the structure and to check the superconducting properties of the investigated samples. Superconducting behavior above liquid nitrogen temperature was evidenced only for the partial substitution of Bi with x = 0.2 Pb and x = 0.1 Sn.


2018 ◽  
Vol 941 ◽  
pp. 1565-1569
Author(s):  
Hitomi Nagasawa ◽  
Masahiko Ikeda ◽  
Masato Ueda

Titanium and its alloys possess high specific strength, excellent corrosion resistance and good biocompatibility [1] [2]. Since oxygen is an unavoidable impurity in such materials, it has been adopted as an alloying element in the development of low-cost titanium alloys. Therefore, it is important to investigate the role of oxygen in these alloys, especially in β-type alloys. In the present study, the effects of oxygen on the electrical resistivity, Vickers hardness and heat treatment behavior of a Ti-20mass%V alloy which is the lowest concentration for which the fully retained β phase is obtained were assessed. The electrical resistivity and Vickers hardness of solution-treated and quenched specimens increased with increasing oxygen content, due to the dissolution of oxygen into the β phase and solid solution hardening, respectively. Upon isothermal aging at 673 K, the addition of O accelerated a-phase precipitation. The addition of O was found to suppress the appearance of the athermal ω phase in the solution-treated and quenched state.


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