scholarly journals Influence of Isothermal ω Transitional Phase-Assisted Phase Transition From β to α on Room-Temperature Mechanical Performance of a Meta-Stable β Titanium Alloy Ti−10Mo−6Zr−4Sn−3Nb (Ti-B12) for Medical Application

2021 ◽  
Vol 8 ◽  
Author(s):  
Jun Cheng ◽  
Jinshan Li ◽  
Sen Yu ◽  
Zhaoxin Du ◽  
Xiaoyong Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Room Temperature ◽  
Mechanical Performance ◽  
Secondary Phase ◽  
Electron Backscattered Diffraction ◽  
Low Temperature Aging ◽  
Osa Treatment ◽  
Transitional Phase ◽  
Temperature Aging

The microstructural evolution and tensile performance of a meta-stable β-type biomedical Ti−10Mo−6Zr−4Sn−3Nb (Ti-B12) alloy subjected to one-stage aging (OSA) and two-stage aging (TSA) are investigated in this work. The OSA treatment is performed at 510°C for 8 h. The TSA treatments are composed of low-temperature aging and high-temperature aging. In the first step, low-temperature aging is conducted at 325°C for 2 h. In the second step, the aging temperature is the same as that in the OSA. The result of the microstructure evolution shows that the precipitated secondary phase after aging is mainly influenced by the process of phase transition. There is a marked difference in the microstructure of the Ti-B12 alloy subjected to the OSA and TSA treatments. The needle-shaped α phases are precipitated in the parent β phase after the OSA treatment. Conversely, the short shuttle-like α phases precipitated after the TSA treatment are formed in the β matrix with the aid of the role of the isothermal ω transitional phase-assisted phase transition. The electron backscattered diffraction results indicate that the crystallographic orientation relationship of the α phases precipitated during the TSA treatment is basically analogous to those in the OSA treatment. The relatively higher tensile strength of 1,275 MPa is achieved by strengthening the effect of the short shuttle-like α precipitation with a size of 0.123 μm in length during the TSA treatment, associating with a suitable elongation of 12% at room temperature simultaneously. The fracture surfaces of the samples after the OSA and TSA treatments indicate that preventing the coarsening of the α layers in the grain boundaries is favorable for the enhancement of strength of Ti-B12 at room temperature. MTT test was carried out to evaluate the acute cytotoxicity and biocompatibility of the implanted material using L929 cells. The relative proliferation rates of cytotoxicity levels 0, 1, 2, 3, and 4 are ≥100, 80–99, 50–79, 30–49, and 0–29%, respectively. The cytotoxicity of the Ti-B12 alloy is slightly better than that of the Ti−6Al−4V alloy, which can meet the requirements of medical materials for biomedical materials.

Influence of Low Temperature Aging on the Flexural Strength of Y-TZP Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1756-1760 ◽  
Author(s):  
Chen Wang ◽  
Li Min Dong ◽  
Yuan Fu Yi ◽  
Ning Wen ◽  
Qing Feng Zan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Low Temperature ◽  
Flexural Strength ◽  
Monoclinic Phase ◽  
Accelerated Aging ◽  
Strength Increase ◽  
Low Temperature Aging ◽  
Temperature Aging

Low temperature aging (LTD) is an important factor of Y-TZP ceramic as artificial joint femoral head and dental restorative materials in vivo for long-term application. In this paper, the accelerated aging experiments on Y-TZP ceramics were conducted. The t-m phase transition is occurring from the surface to the inside during low temperature aging of Y-TZP ceramics. As content of phase transformation increases, thickness of phase transformation layer increases. While the content of surface monoclinic phase is less, the volume expansion and surface stress caused by phase transformation can make cracks and holes shrink or even close, then the flexural strength increase. As a large number of surface monoclinic phase was generated, due to there are a lot of microscopic defects in the phase transition layer, crystals loose, strength of grain boundary lower than that of not aging area and phase transformation layers fracture in the intergranular mode, that damages the flexural strength. Therefore, the flexural strength increase firstly and then decrease with the increase of surface monoclinic content.

Compendium of alloy phases observed after low temperature aging of Ni-rich NiAl

1990 ◽  
Vol 48 (4) ◽  
pp. 944-945
Author(s):  
Ivan E. Locci ◽  
P. S. Khadkikar ◽  
R. D. Noebe ◽  
K. Vedula
Keyword(s):  
Low Temperature ◽  
Room Temperature ◽  
Single Phase ◽  
Tensile Ductility ◽  
Intermetallic Alloys ◽  
Directionally Solidified ◽  
Two Phase ◽  
Low Temperature Aging ◽  
Temperature Aging ◽  
Stable And Metastable Phases

An overwhelming amount of research has been performed on Ni3Al (γ’) and NiAl (β) intermetallic alloys over the last decade. Yet, very little is known about the two phase field between these ordered compounds, including the occurrence and stability of phases other than γ’ or β Identifying and understanding these other phases are important since one approach to improving the ductility and toughness of NiAl is to design an alloy with a dual phase microstructure (i.e. NiAl + Ni3Al). Preliminary alloying attempts have encountered varying degrees of success. They range from powder metallurgy alloys with significantly increased fracture strengths over single phase (β-alloys to directionally solidified γ’ + β crystals which exhibit up to 9% tensile ductility at room temperature. Unfortunately, aging of these alloys at low temperature (<973 K) results in the formation of several complex, stable and metastable phases which may negate any original improvements in mechanical behavior.

Microbiological Studies on Aging of Intact and Excised Beef Muscle1

1978 ◽  
Vol 41 (4) ◽  
pp. 259-262 ◽  
Author(s):  
C. R. REY ◽  
A. A. KRAFT ◽  
F. C. PARRISH
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Aging Treatment ◽  
Bacterial Populations ◽  
Similar Treatment ◽  
Low Temperature Aging ◽  
Retail Cuts ◽  
The University ◽  
Temperature Aging

Beef cattle from the University herd were used for these studies; aging treatments after slaughter were as follows: (a) sides were held at room temperature (21–23 C), (b) sides were held at 2 C, (c) sides were kept for 6 hat room temperature and then the round was removed and placed at 2 C for 18 h (d) sides were held for 3 days at 2 C, then the excised round was kept for 4 days at 2 C for a total of 1 week of low temperature aging. After aging by procedures described, steaks were cut from the round, packaged and stored in a display case at about 5 C. Similar treatment was given to ground beef prepared from the same round muscles. Holding an entire side of beef at high temperature for 24 h promoted bacterial growth on the surface with subsequent proliferation on retail cuts. Shortening the aging treatment at high temperature resulted in reduced bacterial populations on packaged items. Highest bacterial loads and most rapid spoilage resulted from excising the muscle after low temperature holding and then continuing to hold the muscle in the cooler. This treatment was even more conducive to spoilage than was holding at room temperature for 24 h, and is not to be recommended.

Effect of Low Temperature Aging on Internal Friction of AA2024

2012 ◽  
Vol 463-464 ◽  
pp. 41-46
Author(s):  
D.D. Risanti ◽  
Sybrand van der Zwaag
Keyword(s):  
Low Temperature ◽  
Internal Friction ◽  
Room Temperature ◽  
Slow Release ◽  
Peak Height ◽  
Microstructural Changes ◽  
Temperature Range ◽  
Low Temperature Aging ◽  
Anelastic Behavior ◽  
Temperature Aging

The anelastic behavior of AA2024 alloy is studied in the temperature range between room temperature and 325 °C. The internal friction technique is shown to be very sensitive to the microstructural changes that take place at these temperatures. Interrupted aging performed at low temperature induces increase in the peak height at ~230 °C indicating the slow release of vacancies aiding the aggregation of Mg and Cu which further transforms into semicoherent precipitates. Stretched specimens indicate increase in background which is attributed to anelastic or viscoelastic of dislocations. TDIF of T6I4 samples is strongly affected to the point of deformation, whilst TDIF of T6I6 samples is affected by the deformation but irrespective to the point of deformation.

Survival of mouse blastocysts after low-temperature preservation under high pressure

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti
Keyword(s):  
Phase Transition ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
High Hydrostatic Pressure ◽  
Room Temperature ◽  
Freezing Point ◽  
Significant Loss ◽  
Embryo Cryopreservation ◽  
Subzero Temperatures ◽  
Survival Capacity

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

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