scholarly journals The Transformation Process of β-Phase of Cu-Al System and the Effect of Mn Addition Upon it (Second Report)

1949 ◽  
Vol 13 (3) ◽  
pp. 6-10
Author(s):  
Isao Tarora
Keyword(s):  
Transformation Process ◽  
Β Phase

Electropulsing-Induced α to β Phase Transformation of Ti–6Al–4V

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jihui Huang ◽  
Zhutian Xu ◽  
Yujun Deng ◽  
Linfa Peng
Keyword(s):  
Phase Transformation ◽  
Transformation Process ◽  
Transformation Rate ◽  
Avrami Model ◽  
Β Phase ◽  
Specific Effects ◽  
Heating Treatment ◽  
Transus Temperature ◽  
Lower Temperature ◽  
Electropulsing Treatment

Abstract Electrically assisted forming (EAF) has been increasingly utilized as an effective auxiliary processing technology to improve the formability of hard-to-deform metals. Previous works have revealed that the phase transformation of titanium alloys subjected to electropulsing treatment (EPT) can occur at a lower temperature and in a remarkably shorter time compared with those subjected to the traditional heating treatment (THT). However, an in-depth experimental verification and further analysis is still missing so far. Therefore, to characterize the specific effects of EPT on α → β transformation process, both EPT and THT experiments were conducted on Ti–6Al–4V sheet specimens. After that, a calculation method based on the analysis of optical microscopic (OM) metallographs was developed to characterize the amount of phase transformation in EPT and THT. According to the results, it was found that the pulse current can significantly reduce the phase transus temperature and accelerate the transformation process in EPT compared with that in THT. Furthermore, the specific effects of EPT on transus temperature and phase transformation rate were investigated in detail. Based on that, the transformation kinetics of the electropulsing-induced α → β phase transformation was also analyzed using the Johnson–Mehl–Avrami model. It is revealed that the activation energies of both nucleation and growth of phase transformation are reduced by electric current. Hence, the phase transformation can start at a lower temperature and with a higher rate in EPT. The mechanism behind the effects was also discussed in detail in the present work.

scholarly journals Effect of Electropulsing Treatment on Microstructure and Mechanical Properties of a Deformed ZrTiAlV Alloy

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3560 ◽  
Author(s):  
Zhi Nan Yang ◽  
Feng Jiang ◽  
Xu Biao Wang ◽  
Lin Qu ◽  
Yan Guo Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heating Temperature ◽  
Transformation Process ◽  
Heating Process ◽  
Positive Effects ◽  
Β Phase ◽  
Treatment Processes ◽  
Conventional Heat Treatment ◽  
Electropulsing Treatment ◽  
Electron Wind

In contrast to conventional heat treatment processes, electropulsing not only heats an alloy, but also exerts some other positive effects during the heating process. In this paper, the microstructural evolution and mechanical properties of a deformed Zr40Ti5Al4V alloy after electropulsing treatment were investigated. The results showed that when the charging voltage was 2 kV, there was a slight decrease in dislocation density due to the electron wind which softened the alloy even though the highest temperature of the specimen during the treatment was only 86 °C. Increasing the charging voltage to 6 kV not only further increased the heating temperature, but accelerated the phase transformation process of α″ → β → α. The presence of the α phase strengthened the alloy but notably deteriorated its ductility. A full and refined β phase microstructure could be obtained when the charging voltage was increased to 8 kV. This simultaneously increased the strength and ductility of the alloy.

Studies on the transformation process of PVDF from α to β phase by stretching

RSC Advances ◽  
2014 ◽  
Vol 4 (8) ◽  
pp. 3938-3943 ◽  
Author(s):  
Li Li ◽  
Mingqiu Zhang ◽  
Minzhi Rong ◽  
Wenhong Ruan
Keyword(s):  
Transformation Process ◽  
Β Phase

Studies on the transformation process of PVDF film from α to β phase by uniaxial stretch

2021 ◽  
Author(s):  
Chao Zhang ◽  
W. Wei ◽  
H.J Sun ◽  
Q.Y. Zhu
Keyword(s):  
Stretch Ratio ◽  
Transformation Process ◽  
Pvdf Film ◽  
Width Ratio ◽  
Dynamic Mechanical Analyzer ◽  
Uniaxial Stretching ◽  
Drawing Temperature ◽  
Β Phase ◽  
Length Width ◽  
Stretching Process

Abstract Stretching process is an effective method to prepare high β- phase PVDF. PVDF film was prepared by extrusion casting in this paper, then stretched by means of uniaxial-stretching using a DMA(Dynamic mechanical analyzer), the effects of stretching conditions on the transformation from α to β phase of PVDF were studied, also with the changes regularity of mechanical properties during stretching. The phase composition was characterized by XRD, FTIR, DSC, the results show that, the optimum drawing temperature is 80°C, the optimum stretch ratio is related to the length-width ratio of the film, the increase of stretching rate is beneficial to the formation of β-phase, the β-phase can reach 80% under the optimum drawing conditions.

Phase Transformation In Ti-6al-4v Alloys

1972 ◽  
Vol 30 ◽  
pp. 584-585
Author(s):  
Shiro Fujishiro
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Cryogenic Temperature ◽  
Β Phase ◽  
Heat Treated ◽  
Mixed Microstructure ◽  
Ductile Behavior

The Ti-6 wt.% Al-4 wt.% V commercial alloys have exhibited an improved formability at cryogenic temperature when the alloys were heat-treated prior to the tests. The author was interested in further investigating this unusual ductile behavior which may be associated with the strain-induced transformation or twinning of the a phase, enhanced at lower temperatures. The starting materials, supplied by RMI Co., Niles, Ohio were rolled mill products in the form of 40 mil sheets. The microstructure of the as-received materials contained mainly ellipsoidal α grains measuring between 1 and 5μ. The β phase formed an undefined grain boundary around the a grains. The specimens were homogenized at 1050°C for one hour, followed by aging at 500°C for two hours, and then quenched in water to produce the α/β mixed microstructure.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

Structure of a new orthorhombic phase in NiTi: Mn shape memory alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 1000-1001
Author(s):  
Jenö Beyer ◽  
Lajos Tóth
Keyword(s):  
Martensitic Transformation ◽  
Structural Changes ◽  
High Vacuum ◽  
Intermetallic Phase ◽  
Orthorhombic Phase ◽  
Transformation Process ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Crystallographic Structures ◽  
Ternary Additions

The structural changes during reversible martensitic transformation of near-equiatomic NiTi alloys can best be studied in TEM at around room temperature. Ternary additions like Mn offer this possibility by suppressing the Ms temperature below RT. Besides the stable intermetallic phases (Ti2Ni, TiNi, TiNi3) several metastable phases with various crystallographic structures (rhombohedral, hexagonal, monoclinic, cubic) have also been reported to precipitate due to suitable annealing procedures.TiNi:Mn samples with 0.9 and 1.3 at% Mn were arc melted in argon atmosphere and homogenized at 948 °C for 72 hours in high vacuum in an infrared furnace. After spark cutting slices of 0.2 mm, TEM specimens were prepared by electrochemical polishing with the twin-jet technique in methanol - perchloric acid electrolyte. The TEM study was carried out in a JEOL 200 CX analytical electron microscope.In this paper a new intermetallic phase is reported which has been observed in both samples by TEM during the martensitic transformation process.

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