Crack-free functionally graded TiC particle (TiCp) reinforced Ti6Al4V (TiCp/Ti6Al4V) composite was manufactured by laser melting deposition (LMD) technology with TiC volume fraction changing ...gradually from 0% to 50%. This research focuses on the relationship between the microstructure and mechanical properties (microhardness and tensile properties) of TiCp/Ti6Al4V composites under different TiC volume fractions. Besides the unmelted TiC particles, the granular and chain shaped eutectic TiC phases are observed in the composite with 5vol% TiC due to the melting and dissolution of TiC particles into matrix. The granular and dendritic primary TiC phases are obtained in the composite with 10vol% TiC, while the chain shaped eutectic TiC phases can scarcely be seen. The main reinforcement phases are primary TiC phases when the TiC volume fraction exceeds 15%. (i) The quantity of unmelted TiC particles, (ii) the quantity and size of primary TiC phases and (iii) the porosity of composite increase gradually when the TiC volume fraction increases. The interfaces exhibit good bonding between consecutive layers. The microhardness of the functionally graded TiCp/Ti6Al4V composite increases gradually with TiC volume fraction increasing. It is attributed to the C element in solid solution and the appearance of eutectic and primary TiC phases. The microhardness at the top layer with 50vol% TiC is improved by nearly 94% compared with that at the Ti6Al4V side. The tensile strength of TiCp/Ti6Al4V composite with 5vol% TiC is enhanced by nearly 12.3% compared with that of the Ti6Al4V matrix alloy. However, both the tensile strength and elongation of composite decrease gradually when the TiC volume fraction exceeds 5%. The reason is that the quantity of brittle unmelted TiC particles and the quantity and size of dendritic TiC phases increase with TiC volume fraction increasing. The fracture mechanism of the TiCp/Ti6Al4V composite is quasi-cleavage fracture.
It is crucial for dental surgeons to use the mechanical properties of dental prosthetic materials to correlate the submersion time in a mangrove environment.
This study aimed to submerge dental ...prosthetic materials, such as acrylic resin and zirconia, contained within acrylic resin disks in a mangrove environment, and analyze the alterations in mechanical parameters, such as surface roughness and microhardness, to estimate submergence time in similar forensic situations.
A total of 6 specimens was embedded in acrylic resin disks numbered from 1 to 6. The materials were polished for initial parameter readings a day before submersion, and new readings were obtained 1after submersion. All specimens were subjected to surface roughness analysis, in addition to Knoop microhardness analysis for acrylic resin and Vickers microhardness analysis for zirconia. After the experiment, the data were computed for statistical comparation of the materials properties different parameters.
There was a significant increase in surface roughness and Knoop microhardness was reduced in the Acrylic Resin samples (p< 0.05); however, no statistically significant differences were observed in the roughness or Vickers microhardness values of the zirconia samples.
Zirconia prosthetics were more resistant to degradation when submerged in a mangrove environment compared to acrylic resin ones; however, owing to the obstacles inherent in this study, we suggest further research on the properties of prosthetic materials submerged in mangroves or other environments, which could bolster the work of dental professionals in forensic medical institutes.
•Immerse acrylic resin teeth in mangrove increases roughness and decreases hardness.•Immerse zirconia blocks in mangrove doesn’t change the material's properties.•The dental materials mechanical properties changes can estimate time of immersion.•The present results can help forensic sciences on PMI estimation.
Abstract
This study aims to investigate the sliding wear behavior of Al
0.4
FeCrNiCo
x
(
x
= 0, 0.25, 0.5, 1.0 mol) high-entropy alloys (HEAs) under oil lubricating conditions at room temperature. ...Phase and microstructural characterizations of HEAs are performed by utilizing X-ray photoelectron spectroscopy (XRD) and scanning electron microscope (SEM). The compressive yield strength of Al
0.4
FeCrNiCo
x
(
x
= 0, 0.25, 0.5, 1.0 mol) HEAs is observed to decrease from 1169.35 to 257.63 MPa. Plastic deformation up to 75% is achieved in the case of Al
0.4
FeCrNiCo
x
=1
HEA. The microhardness of HEA samples is found to decrease from 377 to 199 HV after the addition of cobalt content from
x
= 0 to 1.0 mol. Thermal analysis is performed using a differential scanning calorimeter. It is confirmed that Al
0.4
FeCrNiCo
x
(
x
= 0, 0.25, 0.5, 1.0 mol) HEAs do not undergo any phase change up to 1000 °C. The specific wear rate of Al
0.4
FeCrNiCo
x
=1
HEA is observed to be highest in all wear conditions. The worn surfaces were analyzed by SEM with attached energy-dispersive spectroscopy, 3D profiling, and X-ray photoelectron spectroscopy (XPS).
Inconel 625, a high-strength superalloy with excellent corrosion resistance, discovers wide applications in critical sectors such as aerospace, nuclear, marine, and petrochemical. Single-Point ...Incremental Forming (SPIF) has appeared as an adequate fabricating process for shaping superalloy components. This work used a systematic approach, implementing Response Surface Methodology (RSM) to explore the influence of SPIF process variables, including tool nose diameter, step size, tool spindle speed, and wall angle, on microhardness (MH) and surface roughness (SR). The experimental results have been analyzed to determine the influencing process variables and their optimal settings, which simultaneously enhance MH and reduce SR of Inconel 625 superalloy truncated cones using analysis of variance and the desirability function analysis approach. The most significant parameters that influence MH and SR were TND and SS, respectively. The development of quadratic models for MH and SR has been completed successfully. The maximum MH of 486.8 HV and minimum SR of 0.432 µm have been obtained at the optimal parametric setting of TND = 15 mm, SS = 0.4 mm, TSS = 900 rpm, and WA = 57.5° with the desirability values for MH, SR and combined are 0.832, 0.933, 0.881 respectively. The F-value of the MH model = 109.18 and SR Model = 78.24 implies that both models are significant and both models have excellent prediction strength. The percentage error between predicted and actual values of MH and SR in confirmation run results is less than 5 %.
•This study introduces the SPIF of Inconel 625, extending its use to critical sectors like aerospace and nuclear demand for high-performance materials, marking a novel approach to fabricating conical shapes.•Utilizing RSM, the research systematically investigates the impact of SPIF process variables on the microhardness and surface roughness of Inconel 625, setting a standard for Inconel 625 superalloy forming.•The study optimizes SPIF parameters to simultaneously improve the microhardness and reduce the surface roughness in Inconel 625 components, showcasing a balanced approach for quality enhancement.•The computation and validation of quadratic models for predicting microhardness and surface roughness based on SPIF parameters represent a major advancement, which shows significant prediction capability with less than 5 % prediction error.•The research identifies critical SPIF parameters and their optimal settings to achieve targeted responses in Inconel 625 components, offering practical guidelines for industry application and enhancing surface quality.
OBJECTIVETo determine the effect of anti-asthmatic inhalers salbutamol and budesonide on the surface microhardness of bovine tooth enamel. MATERIALS AND METHODSThe study was experimental, ...prospective, longitudinal, and comparative. The sample consisted of permanent mandibular incisors, which were prepared in (n = 90) blocks of dental enamel of size 3 × 3 mm and 2 mm thick, separated into 6 groups of 15 specimens each in sterile bottles properly labeled and contained in artificial saliva at 37°C. Three measurements (baseline, 5 days, and 10 days) were performed after immersion to determine the microhardness using a Vickers microdurometer programmed to apply a load of 100 gm for 15 seconds. RESULTSIt was observed that the enamel surface microhardness decreased after 5 and 10 days, after being in contact with the anti-asthmatic inhalers based on salbutamol and budesonide. In addition, it was evidenced that there is a greater decrease in the superficial microhardness of the enamel when comparing the values at the beginning and after 10 days; likewise, the reduction in the microhardness of enamel exposed to budesonide was greater (120.8 kg/mm2) compared to salbutamol (112.3 kg/mm2) (p<0.001). CONCLUSIONThe two anti-asthmatic inhalers studied decreased superficial enamel microhardness, with the budesonide-based inhaler having a greater erosive effect. CLINICAL SIGNIFICANCEThis research allowed us to know the values of the microhardness of the superficial enamel after being exposed to different anti-asthmatic inhalers that are indicated in daily clinical practice. Therefore, it is important to evaluate this microhardness since the use of different inhalers is very prevalent.
The friction stir welding (FSW) has excellent potential compared to other welding processes for joining similar or dissimilar aluminium alloys, which operate severe plastic mixing and high ...temperature to enhanced the mechanical properties of aluminium alloys. In the present work, RSM was used for the mathematical modelling of the FSW input parameters to fabricate AA3003 and AA6061. The empirical correlation was developed to predict the output responses of the FSWed joints at 95% confidence interval (C.I). The developed model reveals that the tool rotational speed (TRS), and welding speed (WS) were the dominating parameters. The increase in TRS, and decrease in WS leads to increased heat input to the welded joints. The C.I reveals that the ultimate tensile strength (UTS), and microhardness increased with increasing TRS. The optimized value of UTS, % strain nad microhardness was observed as 95.8 MPa, 12.18%, and 74.47 HV, respectively, while the optimized value of TRS, WS, and tilt angle (TA) were 1172 rpm, 57.44 mm-min−1, and 1.252° respectively.
Introduction: Microleakage is one of the most important factors in the failure of root canal treatment. Microhardness is one of the physical properties of bioceramics that can be affected by various ...environmental factors such as enviromental humidity. The aim of this study was to evaluation the effect of adding water to semi-setting cement on the microhardness and microleakage of CEM cement.
Methods: 50 single-rooted teeth were selected. Teeth were cut from the CEJ region and the apical 3 mm of the root were trimmed and dentinal blocks with 5 mm height were prepared Peeso reamer size 2 was used to prepare the canal. The teeth were divided into two groups of 23 cases and two groups of 2 positive and negative controls. In the first group, CEM-cement prepared according to the manufacturer's instructions was placed in the canal. In the second group, after adding water to the semi-setting CEM cement mixture, the canal was filled with this cement. The samples were placed in 1% methylene blue for 3 days and then cut. Microleakage was recorded under a stereomicroscope. The microhardness of the samples was measured with Vickers device after mounting in acrylic resin. Statistical analysis was performed using SPSS19 software and Mann-Whitney Kruskal-Wallis and one-way ANOVA tests.
Results: There was a statistically significant difference between the two groups in microleakage (P-Value <0.008) and microhardness (P-Value <0.001).
Conclusion: According to the results of the present study, adding water to the semi-setting CEM cement not only does have a very bad clinical effect, but also may even increase sealling ability.
A model is proposed that makes it possible to calculate the temperature dependence of the microhardness of glass over the entire temperature range from the softening temperature to absolute zero. The ...calculation uses the temperature dependence of the glass enthalpy and the value of its microhardness at the glass transition temperature. The proposed model is tested on the example of glassy selenium. For this, the temperature dependence of the microhardness of selenium on the softening temperature up to 100 K, which is 50 K below its Debye temperature, is measured. Thus, a relationship is established between the strength and thermodynamic properties of glass.
Microstructural characterizations of both W/CuCrZr and W/SS301 (stainless steel 301) joints reveal the favorable bonding of the filler to the substrates and negligible occurrence of inter-diffusions ...(or interfacial reactions) at the W/filler layer interface. The filler layer of W/CuCrZr joint is mainly made up of Cu-based solid solution (Cu (ss)) and intermetallic Ti-Cu phases. In the case of the W/SS301 joint, the filler layer comprises Cu (ss) and intermetallics including Ti-Cu and Ti-Fe. A reaction layer of Fe2Ti with a thickness of about 10μm is formed adjacent to the filler layer through the reaction of Ti with Fe from the SS301 substrate. A diffusion layer containing σ-phase is developed at the interface between the Fe2Ti reaction layer and the SS301 substrate. The mechanical characterizations including microhardness and shear strength of both W/CuCrZr and W/SS301 joints have been performed. The results of microhardness in the interfacial zone are highly related to the joint microstructure.
The current study is focused on the successful fabrication and characterization of microstructure and properties gradient composite made of 3 mm thick sheets of AA5083-O, AA6061-T6, and AA7075-T6 ...alloys using friction stir additive manufacturing (FSAM) technique. Two combinations of four layered FSAM builds (6756 and 7567) were fabricated successfully without any major defects at the optimized process parameters of 850 rpm (tool rotational speed) and 55 mm/min (tool transverse speed). The material mixing, interfacial bonding features, microstructure evolution, and mechanical performance within the stir zones (SZ) were thoroughly examined using advanced characterization techniques. Electron backscatter diffraction (EBSD) analysis confirmed a gradient microstructure along the build depth in both FSAM builds, with average grain sizes decreasing from 52 μm (AA5083), 46 μm (AA6061), and 40 μm (AA7075) in base metals to ∼ 4–7 μm within the SZ. The remarkable grain refinement within the SZ was mainly attributed to the dominant presence of the continuous dynamic recrystallization (CDRX) mechanism. Texture analysis corresponding to pole figures (PFs) and orientation distribution function (ODF) plots reveals the crystallographic texture evolution along the build depth. The prevalent existence of B/ B‾ and C textures throughout all regions of the FSAM builds affirms the presence of ample shear strain during the FSAM procedure. Through thickness miniature tensile and microhardness tests depict the gradient in mechanical performance for both the FSAM builds along the build depth. Microhardness gradients in the range from ∼ 80 HV0.1 to ∼ 145 HV0.1 were observed along the build depth. The axial sample in the build direction shows appreciable strength (265 MPa and 224 MPa) and uniform elongation (28 % and 24 %) for 6756 and 7567 FSAM build, respectively. Furthermore, remarkable strain hardening behaviour corresponding to hardening capacity (Hc) and hardening exponent (n) was noticed for both the axial build samples compared to AA6061-T6 and AA7075-T6 base metals. These findings underscore the potential of FSAM in fabricating functionally gradient composite materials tailored to specific functional requirements.
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•The FSAM technique has been used to fabricate two combination of defect-free FGCM using AA5083-O/AA6061-T6/AA7075-T6 alloys.•Fine-grained microstructure with appreciable material mixing at the interfacial region is noticed within the stir zones.•Tensile properties in the build direction shows remarkable strength and ductility with appreciable strain-hardening behavior.•The dominant presence of recrystallization textures within the SZ confirms the prominent presence of the CDRX mechanism.•The findings underscore the potential of FSAM in fabricating functionally gradient composite materials for specific functional requirements.
