Unveiling the impact of laser power variations on microstructure, corrosion, and stress-assisted surface crack initiation in laser powder bed fusion-processed Ni-Fe-Cr alloy 718

Corrosion and stress-corrosion related failures often compromise the integrity of critical metallic components during their service, raising significant concerns. It is crucial to comprehend the crack initiation mechanism and the impact of alloy microstructure on this crack initiation process. It is known that the introduction of unique microstructures through metal additive manufacturing brings new challenges. This study aims to investigate, for the first time, the effects of microstructural alterations resulting from fluctuations in laser power during laser powder bed fusion on the surface cracking initiation mechanism and electrochemical behaviour of Ni-Fe-Cr alloy 718, which is widely used in applications that require exceptional strength and corrosion resistance. To carry out this investigation, microcapillary electrochemical methods were combined with high-resolution techniques (TEM, SEM, AFM). The findings emphasize the existence of an optimal range of process parameters that effectively mitigate corrosion and crack initiation susceptibility. This work demonstrated that slight deviations in laser power from this optimal value result in diverse alterations at the micro and submicron scales. These alterations include increased subgrain width, porosity, dislocation density, density of nanovoids, and distribution of carbides. Importantly, these changes, particularly in dislocation and nanovoid densities caused by minor variations in process parameters, significantly affect the material's susceptibility to corrosion initiation and stress-assisted surface cracking

Neurocycle Mind-management Approach: Effect on the Resiliency and Wellbeing of Female University Students

Background: The neurocycle model has been developed based on cognitive neuroscience studies and can be applied to manage the functioning of the mind. Objectives: The present study investigated the effectiveness of the neurocycle mind-management approach in the resiliency and wellbeing of female university students. Materials & Methods: This single-subject experimental study was conducted based on the AB model. The research population comprised all single female university students aged 20 to 30 years studying at Khatam University in 2022. The participants were 3 students who attended the training intervention, and one was the control. The study data were collected using Connor and Davidson’s (2003) resilience scale and Ryff’s (1989) psychological wellbeing scale. Data analysis was performed through chart analysis, clinical improvement rate, and reliable change index. Results: The obtained data revealed that the students’ resilience and psychological wellbeing scores increased compared to the baseline and control values. The overall improvement rates of the participants in terms of resilience and psychological wellbeing were 45.23% and 43.89%, respectively, though not clinically significant. In all three participants, the reliable change index in both variables was higher than 1.96, so the impact of the intervention was statistically significant. Based on the follow-up phase results, the effects of the intervention increased after 1 month from the last intervention session, but the improvement was not significant. Conclusion: The neurocycle mind-management technique can be explored and used as an effective intervention to improve female university students’ resilience and psychological wellbeing

Supplementary files.docx

New global indicator for workers’ health: mortality rate from diseases attributable to selected occupational risk factors: supplementary files</p