scholarly journals Assessment of Boron Diffusivities in Nickel Borides by Two Mathematical Approaches

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 555
Author(s):  
Mourad Keddam ◽  
Peter Jurči
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Model ◽  
Inconel 718 ◽  
Experimental Validation ◽  
Boron Concentration ◽  
Mass Conservation ◽  
Phase System ◽  
Inconel 718 Alloy ◽  
Three Phase ◽  
The Mean

In the work of this contribution, two kinetics models have been employed to assess the boron diffusivities in nickel borides in case of Inconel 718 alloy. The first approach, named the alternative diffusion model (ADM), used the modified version of mass conservation equations for a three-phase system whilst the second one employed the mean diffusion coefficient (MDC) method. The boron diffusivities in nickel borides were firstly evaluated in the interval of 1123 to 1223 K for an upper boron concentration of 11.654 wt% in Ni4B3. The boron activation energies in the three phases (Ni4B3, Ni2B and Ni3B) were secondly deduced by fitting the values of boron diffusivities with Arrhenius relations. Finally, these values of energy were compared with the results from the literature for their experimental validation.

scholarly journals A Comparative Analysis of Laser Additive Manufacturing of High Layer Thickness Pure Ti and Inconel 718 Alloy Materials Using Finite Element Method

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 876 ◽  
Author(s):  
Sapam Ningthemba Singh ◽  
Sohini Chowdhury ◽  
Yadaiah Nirsanametla ◽  
Anil Kumar Deepati ◽  
Chander Prakash ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Layer Thickness ◽  
Inconel 718 ◽  
Laser Power ◽  
Scanning Speed ◽  
Laser Additive Manufacturing ◽  
Inconel 718 Alloy ◽  
Melt Pool ◽  
High Layer

Investigation of the selective laser melting (SLM) process, using finite element method, to understand the influences of laser power and scanning speed on the heat flow and melt-pool dimensions is a challenging task. Most of the existing studies are focused on the study of thin layer thickness and comparative study of same materials under different manufacturing conditions. The present work is focused on comparative analysis of thermal cycles and complex melt-pool behavior of a high layer thickness multi-layer laser additive manufacturing (LAM) of pure Titanium (Ti) and Inconel 718. A transient 3D finite-element model is developed to perform a quantitative comparative study on two materials to examine the temperature distribution and disparities in melt-pool behaviours under similar processing conditions. It is observed that the layers are properly melted and sintered for the considered process parameters. The temperature and melt-pool increases as laser power move in the same layer and when new layers are added. The same is observed when the laser power increases, and opposite is observed for increasing scanning speed while keeping other parameters constant. It is also found that Inconel 718 alloy has a higher maximum temperature than Ti material for the same process parameter and hence higher melt-pool dimensions.

Corrosion Behavior of a Selective Laser Melted Inconel 718 Alloy in a 3.5 wt.% NaCl Solution

2021 ◽  
Author(s):  
Yanbing Tang ◽  
Xinwang Shen ◽  
Yanxin Qiao ◽  
Lanlan Yang ◽  
Jian Chen ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Inconel 718 ◽  
Nacl Solution ◽  
Inconel 718 Alloy

scholarly journals Apparent diffusion coefficient for differentiating between benign and malignant hepatic focal lesions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sherif Abugamra ◽  
Aya Yassin ◽  
Asmaa Saber Mostafa Abdel-Rehim ◽  
Dina Sayed Sheha
Keyword(s):  
Hepatocellular Carcinoma ◽  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Focal Lesion ◽  
Benign Lesions ◽  
Focal Lesions ◽  
Significant Difference ◽  
Apparent Diffusion ◽  
Malignant Lesions ◽  
The Mean

Abstract Background The aim of this study was to prospectively evaluate the role of diffusion weight MRI (DWI) in the characterization of hepatic focal lesions by using apparent diffusion coefficient (ADC). Thirty patients (18 women, 12 men; mean age 48.5 years) with hepatic focal lesions were included in this study. Patients underwent DW MR imaging with the SPLICE sequence. ADC of each focal lesion carcinoma was calculated from DW MR Images obtained with low and high b values. ADCs were compared among pathological types of focal lesions. Results Among the 30 patients included in the study, 46 focal lesions were detected. Twenty-four lesions were metastatic lesions from primary cancer, 7 lesions were hepatocellular carcinoma (HCC), 9 lesions were hemangiomas, and 6 lesions were simple cysts. There was highly significant difference between the mean ADC of the malignant lesions (metastasis and HCC) and the mean ADC of benign lesions (hemangiomas and cysts). The ADC of malignant lesion was much less than that of benign lesion. The mean ADC of malignant lesions (n = 31) was 0.73 ± 0.19 × 10−3 mm2/s, and the mean ADC of benign lesions (n = 15) was 1.94 ± 0.68 × 10−3 mm2/s (p value < 0.001). There was no significant difference between the cysts and hemangiomas. There was no statistically significant difference between the metastases and hepatocellular carcinoma. Conclusion ADCs values were able to differentiate benign from malignant lesions. ADC should be considered in the work up of patients with hepatic focal lesions.

scholarly journals Very-High-Cycle Fatigue Behavior of Inconel 718 Alloy Fabricated by Selective Laser Melting at Elevated Temperature

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1001
Author(s):  
Zongxian Song ◽  
Wenbin Gao ◽  
Dongpo Wang ◽  
Zhisheng Wu ◽  
Meifang Yan ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Selective Laser Melting ◽  
Fatigue Resistance ◽  
Inconel 718 ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Laser Melting ◽  
Inconel 718 Alloy ◽  
Very High Cycle Fatigue ◽  
Very High

This study investigates the very-high-cycle fatigue (VHCF) behavior at elevated temperature (650 °C) of the Inconel 718 alloy fabricated by selective laser melting (SLM). The results are compared with those of the wrought alloy. Large columnar grain with a cellular structure in the grain interior and Laves/δ phases precipitated along the grain boundaries were exhibited in the SLM alloy, while fine equiaxed grains were present in the wrought alloy. The elevated temperature had a minor effect on the fatigue resistance in the regime below 108 cycles for the SLM alloy but significantly reduced the fatigue strength in the VHCF regime above 108 cycles. Both the SLM and wrought specimens exhibited similar fatigue resistance in the fatigue life regime of fewer than 107–108 cycles at elevated temperature, and the surface initiation mechanism was dominant in both alloys. In a VHCF regime above 107–108 cycles at elevated temperature, the wrought material exhibited slightly better fatigue resistance than the SLM alloy. All fatigue cracks are initiated from the internal defects or the microstructure discontinuities. The precipitation of Laves and δ phases is examined after fatigue tests at high temperatures, and the effect of microstructure on the formation and the propagation of the microstructural small cracks is also discussed.

Microstructure and Wear Properties of Laser-clad NiCo Alloy Coating on Inconel 718 Alloy

2021 ◽  
pp. 160412
Author(s):  
Tao Wang ◽  
Chao Wang ◽  
Juanjuan Li ◽  
Linjiang Chai ◽  
Xing Hu ◽  
...  
Keyword(s):  
Inconel 718 ◽  
Alloy Coating ◽  
Wear Properties ◽  
Inconel 718 Alloy
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