Atomic imaging of the interface between M23C6-type carbide and matrix in a long-term ageing polycrystalline Ni-based superalloy

2015 ◽  
Vol 95 (4) ◽  
pp. 237-244 ◽  
Author(s):  
X.B. Hu ◽  
Y.L. Zhu ◽  
L.Z. Zhou ◽  
B. Wu ◽  
X.L. Ma
Keyword(s):  
M23c6 Type ◽  
Type Carbide

Changes in Microstructure of Biomedical Co-Cr-Mo-C Alloys with Solution Treating and Aging

2010 ◽  
Vol 89-91 ◽  
pp. 377-382 ◽  
Author(s):  
S. Mineta ◽  
Shigenobu Namba ◽  
Takashi Yoneda ◽  
Kyosuke Ueda ◽  
Takayuki Narushima
Keyword(s):  
Solution Treatment ◽  
Heating Time ◽  
Treatment Temperature ◽  
Vacuum Furnace ◽  
Solution Treatment Temperature ◽  
Precipitate Dissolution ◽  
Heat Treated ◽  
M23c6 Type ◽  
Type Carbide ◽  
Time Required

Microstructural changes occurring in biomedical Co-Cr-Mo alloys with three carbon levels due to solution treatment and aging were investigated. Ingots of Co-Cr-Mo alloys with three different carbon levels were prepared by vacuum furnace melting; their chemical composition was Co-28Cr-6Mo-xC (x = 0.12, 0.25 and 0.35 mass%). Precipitates were electrolytically extracted from as-cast and heat-treated alloys. An M23C6 type carbide and a phase were detected as precipitates in as-cast Co-28Cr-6Mo-0.12C alloy, and an M23C6 type carbide and an  phase (M6C-M12C type carbide) were detected in as-cast Co-28Cr-6Mo-0.25C and Co-28Cr-6Mo-0.35C alloys. Only the M23C6 type carbide was detected during solution treatment. Complete precipitate dissolution occurred in all the three alloys after solution treatment. The holding time required for complete precipitate dissolution increased with increasing carbon content and decreasing solution treatment temperature. Complete precipitate dissolution occurred in the Co-Cr-Mo-C alloys solution treated at 1523 K for 43.2 ks; they were then subjected to aging from 873 to 1473 K for a heating time up to 44.1 ks after complete precipitate dissolution in solution treatment at 1523 K for 43.2 ks. The M23C6 type carbide with a grain size of 0.1–3 m was observed after aging. A time-temperature-precipitation diagram of the M23C6 type carbide formed in the Co-28Cr-6Mo-0.25C alloy was plotted.

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.

Precipitation of Nano-Sized Z-Phase in HR3C Austenitic Heat Resistant Steel

2013 ◽  
Author(s):  
Fengshi Yin ◽  
Zhen Xu ◽  
Bing Xue ◽  
Li Zhou ◽  
Xuebo Jiang
Keyword(s):  
Aging Temperature ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Resistant Steel ◽  
Secondary Phases ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
M23c6 Type ◽  
Type Carbide ◽  
Austenite Grains

Effect of heat treatment on the precipitation behavior of secondary phases in a HR3C austenitic heat resistant steel was investigated. The microstructure of the steel in solution-treated state consists of austenitic matrix and coarse Z-phase particles. After aging treatment at 650–950°C for 1h, M23C6-type carbide precipitates along random grain boundaries. Dense and homogeneous nanosized Z-phase precipitates within austenite grains are obtained by an aging treatment at a temperature between 800 and 900°C for 1h. The high density of dislocation walls produced during the water-cooling process after solution treatment facilitate the precipitation of the nanosized Z-phase. With increasing the aging temperature, the hardness initially drops, then increases and reaches a peak when the aging temperature is at 850°C due to the precipitation of the nanosized Z-phase.

Effects of Electropulsing Treatment on the Precipitation Behaviour of Grain Boundary Carbides in GH3044 Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 464-467 ◽  
Author(s):  
Yang Liu ◽  
Lei Wang ◽  
Yu Chen Wang ◽  
Hong Yan Liu ◽  
Xue Jiao Chen ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Current Density ◽  
Pulse Width ◽  
High Current Density ◽  
Aging Treatment ◽  
Volume Percentage ◽  
Precipitation Behaviour ◽  
M23c6 Type ◽  
Type Carbide ◽  
Electropulsing Treatment

The effects of electropulsing treatment on the precipitation behaviour of grain boundary carbides in GH3044 alloy were investigated. The results showed that the initial temperature of precipitation of M23C6 type carbides on grain boundary could be decreased by electropulsing treatment under the condition of high current density of 10.0kA/mm2 with a frequency of 5Hz and pulse width of 15s. The volume percentage of M23C6 type carbide was greatly increased to 274.60% comparing with that of the aging treatment at the same temperature. However, the precipitation of M23C6 type carbide was inhibited by electropulsing treatment under the condition of high frequency of 45Hz with the current density of 2kA/mm2 and pulse width of 15s. The volume percentage of M23C6 type carbide was decreased to 18.81% comparing with that of the aging treatment at the same temperature. It has been found that the diffusion of solute atom in the alloy can be promoted by the electric effect with the electropulsing. As a result, the thermodynamic condition and kinetics of the precipitation of M23C6 type carbide were changed, and both the initial and peak temperatures of precipitation were decreased.

Heat Treatment of ASTM F75 Co-Cr-Mo-C-Si-Mn Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 2180-2183 ◽  
Author(s):  
Alfirano ◽  
Shingo Mineta ◽  
Shigenobu Namba ◽  
Takashi Yoneda ◽  
Kyosuke Ueda ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Intermetallic Phase ◽  
Solution Treatment ◽  
Metallic Phase ◽  
Precipitate Dissolution ◽  
Carbide Dissolution ◽  
M23c6 Type ◽  
Type Carbide ◽  
Astm F75

In this study, the carbide dissolution and formation of biomedical Co-28Cr-6Mo-0.25C-1Si (1Si) and Co-28Cr-6Mo-0.25C-1Mn (1Mn) alloys occurring during solution treatment and aging were investigated. The addition of Si or Mn markedly affected the behavior of precipitates during heat treatment. The alloy with added Si required a longer solution treatment time for complete precipitate dissolution as compared to the alloy with added Mn. Blocky M23C6-type carbide was observed during solution treatment at 1448–1523 K. Starlike precipitates were observed in the 1Si and 1Mn alloys at 1523–1548 K and 1523 K, respectively. The starlike precipitates exhibited two types of morphologies: dense and stripe patterned. The starlike precipitates with dense and stripe-patterned appearances were a -phase and M23C6¬-type carbide + metallic -phase, respectively. An M23C6-type carbide and an -phase were formed during the aging of both the 1Si and the 1Mn alloys. In addition, an intermetallic -phase was detected during the aging of the 1Si alloy at 1373 K.

Effect of ECAP on the Microstructure and Mechanical Properties of 17-4PH Stainless Steel

2010 ◽  
Vol 667-669 ◽  
pp. 879-884 ◽  
Author(s):  
Gang Yang ◽  
Feng Shi Yin
Keyword(s):  
Mechanical Properties ◽  
Tempering Temperature ◽  
Angular Pressing ◽  
Ecap Process ◽  
Solution Treated ◽  
Tensile Impact ◽  
Microstructure And Mechanical Properties ◽  
Tempering Treatment ◽  
M23c6 Type ◽  
Type Carbide

Experiments were conducted to evaluate the influence of equal-channel angular pressing (ECAP) on the microstructure and mechanical properties of 17-4PH steel. The 17-4PH steel was solution-treated at 1040°C for 1h followed by oil cooling before ECAP process. Both the as solution-treated and ECAPed specimens were tempered at 460°C and 610°C for 2h, respectively. Tensile, impact and hardness properties as well as the microstructure and fracture mode were systematically studied. The results show that both the tensile strength and hardness are increased by ECAP process, the elongation is deceased but the Charpy V-notch energy absorption is increased by ECAP process when the tempering treatment is at a low temperature of 460°C, while the result is just reverse when the tempering temperature is 610°C. SEM observation reveals that the ECAP process promotes the precipitation of M23C6-type carbide obviously. The relations among ECAP process, microstructure, mechanical properties and fracture modes are discussed.

scholarly journals Microstructure of a V-Containing Cobalt Based Alloy Prepared by Mechanical Alloying and Hot Pressed Sintering

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 464 ◽  
Author(s):  
Niannian Li ◽  
Fengshi Yin ◽  
Liu Feng
Keyword(s):  
Mechanical Alloying ◽  
Amorphous State ◽  
High Hardness ◽  
High Energy ◽  
Hardness Tests ◽  
M23c6 Type ◽  
Energy Ball ◽  
Type Carbide ◽  
Carbide Particles ◽  
Prepared Alloy

In this paper, a bulk V-containing cobalt-based alloy with high chromium and tungsten contents was prepared by mechanical alloying and hot pressed sintering using Co, Cr, W, Ni, V and C pure element powders. XRD, SEM, TEM and Vickers hardness tests were employed to characterize the microstructure and mechanical properties of the mechanical alloyed powders and hot pressed bulk cobalt-based alloy. The results show that all elements can be mixed uniformly and that the Co, Cr, and Ni elements were made into an amorphous state after 10 h ball milling in a high energy ball miller. The microstructure of the prepared bulk alloy was composed of a γ-Co matrix with a large number of nano-twins and fine M23C6 and M12C carbide particles well-distributed in the alloy. The V element was mainly distributed in M23C6-type carbide and no V-rich MC-type carbide was found in the microstructure. The prepared alloy had a high hardness of 960 ± 9.2 HV and good a fracture toughness KIc of about 10.5 ± 0.46 MPa·m1/2. The microstructure formation and strengthening mechanisms of the prepared cobalt-based alloy are discussed.

Therapy and prevention for mental health: What if mental diseases are mostly not brain disorders?

2019 ◽  
Vol 42 ◽  
Author(s):  
John P. A. Ioannidis
Keyword(s):  
Mental Health ◽  
Mental Disease ◽  
Brain Disorders ◽  
Social Stressors ◽  
Labor Education ◽  
Mental Diseases ◽  
Long Term Follow Up ◽  
Political Decisions

AbstractNeurobiology-based interventions for mental diseases and searches for useful biomarkers of treatment response have largely failed. Clinical trials should assess interventions related to environmental and social stressors, with long-term follow-up; social rather than biological endpoints; personalized outcomes; and suitable cluster, adaptive, and n-of-1 designs. Labor, education, financial, and other social/political decisions should be evaluated for their impacts on mental disease.

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