Precipitates in Biomedical Co-Cr-Mo-C-Si-Mn Alloys

2011 ◽  
Vol 277 ◽  
pp. 51-58 ◽  
Author(s):  
T. Narushima ◽  
Alfirano ◽  
S. Mineta ◽  
Shigenobu Namba ◽  
Takashi Yoneda ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Temperatures ◽  
Metallic Matrix ◽  
Carbon Activity ◽  
Holding Time ◽  
Dissolution Behavior ◽  
Stripe Pattern ◽  
Compound C ◽  
Heat Treated ◽  
Type Carbide

The phase and dissolution behavior of precipitates in biomedical ASTM F75 Co-Cr-Mo-C-Si-Mn alloys were investigated. Alloys of five different compositions, Co-28Cr-6Mo-0.25C-1Si, Co-28Cr-6Mo-0.25C-1Mn, Co-28Cr-6Mo-0.25C-1Si-1Mn, Co-28Cr-6Mo-0.15C-1Si, and Co-28Cr-6Mo-0.35C-1Si, were heat-treated from 1448 to 1548 K. The precipitates observed in the as-cast and heat-treated alloys were carbides (M23C6type, h-phase, and p-phase) and an intermetallic compound (c-phase). The main precipitates observed after heat treatment at high temperatures such as 1548 K were p-phase and M23C6type carbide. At these high temperatures, two types of starlike precipitates—dense and stripe-patterned—were observed. The starlike-dense precipitate was the p-phase, and the starlike precipitate with a stripe pattern was identified as the M23C6type carbide and metallic fcc g-phase. In the alloys heat-treated at 1448 to 1498 K, blocky-dense M23C6type carbide was primarily observed. c-phase was detected in the Co-28Cr-6Mo-0.15C-1Si alloy under as-cast condition and after heat treatment at 1448–1523 K for a short holding time. The addition of Si seemed to increase the holding time for complete precipitate dissolution because of the effects of Si on the promotion of p-phase formation at high temperatures and the increased carbon activity in the metallic matrix.

Phase and Morphology of Carbides in ASTM F75 Co-Cr-Mo-C Alloys Formed at 1473 to 1623 K

2010 ◽  
Vol 654-656 ◽  
pp. 2176-2179 ◽  
Author(s):  
Shingo Mineta ◽  
Alfirano ◽  
Shigenobu Namba ◽  
Takashi Yoneda ◽  
Kyosuke Ueda ◽  
...  
Keyword(s):  
Carbon Content ◽  
Complete Dissolution ◽  
Stripe Pattern ◽  
Precipitate Dissolution ◽  
Solution Treated ◽  
Heat Treated ◽  
Cast Alloys ◽  
M23c6 Type ◽  
Type Carbide ◽  
Astm F75

The phase and morphology of precipitates in heat-treated Co-28Cr-6Mo-xC (x = 0.12, 0.15, 0.25, and 0.35mass%) alloys were investigated. The as-cast alloys were solution-treated in the temperature range of 1473 to 1623 K for 0 to 43.2 ks. Complete precipitate dissolution was observed in all four alloys, each of which had different carbon contents. The holding time for complete dissolution was greater for alloys with greater carbon content. The curve representing the boundary between the complete- and incomplete-dissolution conditions for each alloy is C shaped. Under the incomplete precipitate dissolution conditions of the Co-28Cr-6Mo-0.25C alloy, an M23C6 type carbide and a π-phase (M2T3X type carbide with β-Mn structure) were observed at 1548 to 1623 K, and starlike precipitates with a stripe pattern and with a dense appearance were both observed; the former comprised the M23C6 type carbide + γ-phase, and the latter was the π-phase. In contrast, only a blocky-dense M23C6 type carbide was observed at 1473 to 1523 K.

Microstructural and Vickers Microhardness Evolution of Heat Treated Secondary Aluminium Cast Alloy

2013 ◽  
Vol 586 ◽  
pp. 137-140 ◽  
Author(s):  
Lenka Hurtalová ◽  
Eva Tillová ◽  
Mária Chalupová
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Artificial Aging ◽  
Vickers Microhardness ◽  
Cast Alloy ◽  
Solution Treatment ◽  
Holding Time ◽  
Age Hardening ◽  
Structural Components ◽  
Heat Treated

Secondary aluminium alloys are made out of aluminium scrap and aluminium-processable waste by recycling. These alloys contain different alloying elements such as Al, Cu, Fe, Si and Mg that form intermetallic phases in aluminium matrix and influence on the microstructure, basic mechanical properties and microhardness evolution in aluminium cast alloy. As experimental material was used secondary aluminium cast alloy AlSi9Cu3. Material was subjected to heat treatment (age-hardening) consisting of a solution treatment at temperature 515 °C with holding time 4 hours, than water quenching at 40 °C and artificial aging by different temperature 130 °C, 150 °C and 170 °C with different holding time (2, 4, 8, 16 and 32 hours). The age-hardening led to changes in the morphology of structural components, but also leads to precipitation of finer hardening phases in the material substructure. As optimal age-hardening mode for secondary aluminium cast alloy AlSi9Cu3 was determined mode consisting of solution treatment at temperature 515 °C with holding time 4 hours and artificial aging at temperature 170 °C with holding time 16 hours. After this heat treatment cast alloy shows the best changes in microstructure and mechanical properties. These changes are comparable with changes by primary AlSi9Cu3 cast alloy.

scholarly journals Effect of Heat Treatment on the Compressive Behavior of Zinc Alloy ZA27 Syntactic Foam

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 792 ◽  
Author(s):  
Nima Movahedi ◽  
Graeme Murch ◽  
Irina Belova ◽  
Thomas Fiedler
Keyword(s):  
Heat Treatment ◽  
Microstructural Analysis ◽  
Syntactic Foam ◽  
Metallic Matrix ◽  
Ductile Deformation ◽  
Zinc Alloy ◽  
Syntactic Foams ◽  
Compression Tests ◽  
Static Compression ◽  
Heat Treated

Zinc alloy (ZA27) syntactic foams (SF) were manufactured using expanded perlite (EP) particles and counter-gravity infiltration casting. Due to a variation of the metallic matrix content, the density of the produced foam samples varied from 1.78 to 2.03 g·cm−3. As-cast and solution heat-treated samples were tested to investigate the compressive properties of the ZA27 syntactic foam. To this end, quasi-static compression tests were conducted. In addition, microstructural analysis of the as-cast and heat-treated syntactic foams was carried out using scanning electron microscopy. The results indicate that the heat treatment alters the microstructure of the ZA27 alloy matrix from a multiphase dendrite to a spheroidized microstructure with improved ductility. Moreover, the heat treatment considerably enhances the energy absorption and plateau stress ( σ pl ) of the syntactic foam. Optical analysis of the syntactic foams under compression shows that the dominant deformation mechanism of the as-cast foams is brittle fracture. In comparison, the heat-treated samples undergo a more ductile deformation.

The influence of radiant heat load on reproduction in the Merino ewe. III.* Duration of oestrus, cyclical oestrous activity, plasma progesterone, LH levels and fertility of ewes exposed to high temperatures before mating

1979 ◽  
Vol 30 (6) ◽  
pp. 1151 ◽  
Author(s):  
GJ Sawyer ◽  
DR Lindsay ◽  
GB Martin
Keyword(s):  
Heat Treatment ◽  
High Temperatures ◽  
Critical Period ◽  
Radiant Heat ◽  
Oestrous Cycle ◽  
Control Group ◽  
Cycle Duration ◽  
Ambient Temperatures ◽  
Heat Treated ◽  
Before And After

The effects of high ambient temperatures on the length of the oestrous cycle, duration of oestrus, ovulation rate, fertility and the levels of luteinizing hormone (LH) and progesterone in blood were examined in mature Merino ewes. In experiments 1 and 2, after synchronization of oestrus half the ewes in a group were exposed to hot-room conditions for 6 days prior to the onset of the next expected oestrus. Conditions in the control pen and hot room were, respectively, 22–24°C with vapour pressure 2.10 kPa and 40.0–41.5°C, 2.80–3.50 kPa. In experiment 1, blood samples were taken 4-hourly for 2 days before and after expected oestrus, and analysed for LH and progesterone. In experiment 3, two of three groups of synchronized ewes were exposed to hot-room conditions for days 8–11 inclusive and days 12.5–15.5 inclusive of the oestrous cycle after synchronizing. In all experiments the two heat-treated groups had significantly higher rectal temperatures and respiration rates during treatment than the third (control) group. In experiments 1 and 2 approximately one-third of the heat-treated ewes did not display oestrus, although all ewes in experiment 1 had LH peaks and ovulated. Interference with cyclical oestrous activity was confined to the oestrus immediately after heating. In experiment 2, heat treatment before mating reduced by 30–50% the period that most ewes were receptive to the ram, and one-third did not show oestrus. Ewes heat-treated for 2–3 days immediately before oestrus showed oestrus for a significantly shorter time than those heat-treated between days 8 and 11 of the cycle or controls. Oestrus was completely blocked in 35% of ewes only when heating lasted 6 days and included the critical period immediately before oestrus. If heating was restricted to the critical period, only the duration of oestrus was affected. The oestrous cycle during which treatment was imposed was up to 4 days longer (mean 1.7 days) in most ewes heated prior to oestrus in experiment 1, and by an average of 0.6 day in experiment 2. Progesterone in venous plasma of these heat-treated ewes remained high for longer than in controls, and consequently the LH surge before ovulation was delayed. The fertility of ewes which showed oestrus after heat treatment was not affected, and heated ewes and controls had similar ovulation rates. High temperatures may cause disruption to cyclical oestrous activity by (a) blocking behavioural oestrus, (b) reducing the duration of oestrus, or(c) increasing the length of the oestrous cycle. The severity of such effects depends upon both the duration of heating and on the stage of the oestrous cycle when ewes are exposed. It is suggested that some of the observed disruptions may have a hormonal basis, and possible interference with hormonal or neural mechanisms which determine behavioural oestrus is discussed. ______________________ *Part II, Aust. J. Agric. Res., 30: 1143 (1979).

Precipitation and Dissolution Behavior of δ Phase in Alloy GH4169G

2013 ◽  
Vol 747-748 ◽  
pp. 760-764 ◽  
Author(s):  
Fang Liu ◽  
Lian Xu Yu ◽  
Li Tao Chang ◽  
Xin Xin ◽  
Wei Hong Zhang ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Annealing Temperature ◽  
Laves Phase ◽  
Holding Time ◽  
Dissolution Behavior ◽  
Cast Ingot ◽  
Interdendritic Area ◽  
Phase Dissolution ◽  
Heat Treated ◽  
Δ Phase

The precipitation and dissolution behavior of δ phase at varied states including as cast, heat treated and thermal processed of GH4169G alloy, have been investigated. The results indicated that δ phase existed in the vicinity of Laves phase and carbides with mainly the rod-like, needle-like morphology, and lath-like morphology because of the segregation of Nb in the interdendritic area. The amount of the δ phase decreased with the increase of the annealing temperature, and the dissolution rate increased with the increase of the annealing temperature. After initial holding of 2 h at 1020°C, the residual δ phase fully dissolved at 1140°C for 20min for the as-cast ingot. The minimum holding time for δ phase dissolution at 1020°C was 2h.

Effect of Heat Treatment Parameters on Mechanical Properties of Medium Carbon Steel

2020 ◽  
Vol 22 (4) ◽  
pp. 909-918 ◽  
Author(s):  
M. M. Blaoui ◽  
M. Zemri ◽  
A. Brahami
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cooling Rate ◽  
Heating Rate ◽  
Physical And Mechanical Properties ◽  
Medium Carbon Steel ◽  
Holding Time ◽  
Austenitization Temperature ◽  
Heating And Cooling ◽  
Heat Treated

AbstractEngineering materials, mostly steel, are heat treated under controlled sequence of heating and cooling to alter their physical and mechanical properties to meet desired engineering applications. This paper presents a study of the influence of austenitization temperature, cooling rate, holding time and heating rate during the heat treatment on microstructure and mechanical properties (tensile strength, yield strength, elongation and hardness) of the C45 steel. Specimens undergoing different heat treatment lead to various mechanical properties which were determined using standard methods. Microstructural evolution was investigated by scanning electron microscopy (SEM). The results revealed that microstructure and hardenability of the C45 steel depends on cooling rate, austenitization temperature, holding time and heating rate.

Influence of Air Heat Treatment on Bonding Strength and Microstructure of Al2O3-13wt%TiO2/NiCrAl Coating

2015 ◽  
Vol 817 ◽  
pp. 158-163
Author(s):  
Guo Wei Wang ◽  
Ze Hua Zhou ◽  
Ze Hua Wang ◽  
Han Liu ◽  
Jia Shao ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Bonding Strength ◽  
Holding Time ◽  
Micro Structure ◽  
Cooling Method ◽  
Heat Treated ◽  
Heating Up ◽  
Cooling Methods ◽  
Better Than

Owing to typical weaknesses of Al2O3-13wt%TiO2/NiCrAl coating (AT13), appropriate air heat treatment is an effective method in improving the bonding strength and microstructure of AT13. AT13 was air heat-treated with varying holding times and cooling methods. The aims are not only to ascertain the changes of the bonding strength and micro-structure of AT13 under various conditions, but also to understand the influence of holding time and cooling method on the bonding strength and microstructure of the coating. The experimental results showed that the best bonding strength and lowest porosity of AT13 were obtained using proper heat treatment of heating up to 560°C for 6 h along with two-step cooling. The two-step cooling is better than normal furnace cooling in improving properties of the coating, which is attributed to the densification of AT13 and release of residual stress.

Characterization and Dissolution Behavior in a Physiological Solution of Heat-Treated CaTiO3 Thin Films with Different Thicknesses

2007 ◽  
Vol 127 ◽  
pp. 209-214
Author(s):  
Naofumi Ohtsu ◽  
Kesami Saito ◽  
Katsuhiko Asami ◽  
Takao Hanawa ◽  
Hisamichi Kimura
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Incident Angle ◽  
Titanium Substrate ◽  
Physiological Solution ◽  
Dissolution Behavior ◽  
Nacl Solution ◽  
Heat Treated ◽  
Perovskite Type

Characterization of heat-treated CaTiO3 thin films of 10, 20, 30 and 50 nm in thickness and their change after immersion in a simulated body fluid were investigated by grazing incident angle X-ray diffractometry and Auger electron spectroscopy (AES). The CaTiO3 films were prepared on titanium substrate by sputter-deposition of CaTiO3 target followed by heating in an electric furnace at 873 K in air for 7.2 ks. The CaTiO3 films were immersed in 0.8% NaCl solution for 14 d. All the films before heat treatment were non-crystallized films and after heat treatment, only the 50-nm film was crystallized to perovskite-type CaTiO3. In AES in-depth profiles after heating, Ca diffusion was not observed in the 50-nm film, whereas Ca diffusion toward the Ti substrate was observed in the 10-, 20- and 30-nm films. After immersion for 14 d, the vicinity of surface of the 10, 20 and 30 nm thick CaTiO3 films were dissolved into the NaCl solution, while the 50-nm thick CaTiO3 film was scarcely dissolved. Since dissolution from biomaterials in a human body has possibility to harm, the CaTiO3 film should be deposited more than 50 nm in thickness and heat-treated at 873 K.

Effect of a Complex Heat Treatment on the Structure of 300M Steel

1981 ◽  
Vol 39 ◽  
pp. 312-313
Author(s):  
R. Padmanabhan ◽  
W. E. Wood
Keyword(s):  
Heat Treatment ◽  
Metal Carbides ◽  
Austenite Grain Size ◽  
300M Steel ◽  
Heat Treated ◽  
Strain Fracture ◽  
Prior Austenite Grain Size ◽  
Short Time ◽  
Final Tempering ◽  
Similar Yield

Intermediate high temperature tempering prior to subsequent reaustenitization has been shown to double the plane strain fracture toughness as compared to conventionally heat treated UHSLA steels, at similar yield strength levels. The precipitation (during tempering) of metal carbides and their subsequent partial redissolution and refinement (during reaustenitization), in addition to the reduction in the prior austenite grain size during the cycling operation have all been suggested to contribute to the observed improvement in the mechanical properties. In this investigation, 300M steel was initially austenitized at 1143°K and then subjected to intermediate tempering at 923°K for 1 hr. before reaustenitizing at 1123°K for a short time and final tempering at 583°K. The changes in the microstructure responsible for the improvement in the properties have been studied and compared with conventionally heat treated steel. Fig. 1 shows interlath films of retained austenite produced during conventionally heat treatment.

“In vitro” and in Animal Model Studies on a Double Virus- Inactivated Factor VIII Concentrate

1995 ◽  
Vol 74 (03) ◽  
pp. 868-873 ◽  
Author(s):  
Silvana Arrighi ◽  
Roberta Rossi ◽  
Maria Giuseppina Borri ◽  
Vladimir Lesnikov ◽  
Marina Lesnikov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Animal Model ◽  
Factor Viii ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Virus Inactivation ◽  
Enveloped Viruses ◽  
Model Studies ◽  
Heat Treated

SummaryTo improve the safety of plasma derived factor VIII (FVIII) concentrate, we introduced a final super heat treatment (100° C for 30 min) as additional virus inactivation step applied to a lyophilized, highly purified FVIII concentrate (100 IU/mg of proteins) already virus inactivated using the solvent/detergent (SID) method during the manufacturing process.The efficiency of the super heat treatment was demonstrated in inactivating two non-lipid enveloped viruses (Hepatitis A virus and Poliovirus 1). The loss of FVIII procoagulant activity during the super heat treatment was of about 15%, estimated both by clotting and chromogenic assays. No substantial changes were observed in physical, biochemical and immunological characteristics of the heat treated FVIII concentrate in comparison with those of the FVIII before heat treatment.

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