Additive manufacturing (AM) is an emerging process that has been extremely improved in terms of technology and application in recent years. In this technology review, new industrial improvements in laser powder bed fusion (LPBF) of metals are discussed. LPBF has the lowest build rate among all AM processes that produce metals such as electron beam powder bed fusion, direct energy deposition, binder jetting and sheet lamination. The findings of the current research show that the most innovations and future directions of LPBF printers are toward increasing the speed of the process by using interchangeable feedstock chamber, closed-loop control powder handling, automated powder sieving, multi-layer concurrent printing, 2-axis coating and multi powder hoppers. To increase the speed of the process, the new improvements for transferring time and using fast lasers are presented. Another innovation in the building of LPBF printers is enhancing part quality by improving lasers with the shorter beam diameter, multi-lasers, uniform inert gas flow, accurate positioning systems, using high vacuum systems and using sensors and automation.

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In the current article, subject-related research metrics by the most popular scientometrics platforms with the capability of citation count are investigated. Different quantitative analyses have been carried out to classify the most to the least cited subject areas that are useful to show the most active and dynamic fields in research. Subject areas are classified based on the statistical analyses and number of received citations in the period of search. Numerous articles were analysed from top-ranked journals in all research fields introduced by Scimago journal classification. The comprehensive dataset was generated in 27 research subject areas including 315 subject categories and 81 high-ranked journals. The overlap of investigated citations was not taken to the account. To remove the effect of overlap of publications that are indexed by more than one platform, the obtained results are compared and analysed independently. Results showed that the highest number of citations was related to sciences and subject areas that are deeper in research. WoS showed better performance over Scopus for subject-related evaluations that is related to the recent expansions on coverage of different materials such as textbooks and proceedings. Some subject areas such as computer science due to highly-dynamic nature and mathematics because of difficulty in concepts were found to have the lowest research metrics and the lowest number of high-cited publications in the period of this investigation. Results of histogram analysis showed Google Scholar (GS) cited less publication for low-cited papers than Scopus and Web of Science (WoS). In contrast, for high-cited publications, GS found to have higher performance that is related to the Matthew effect. WoS found to have the best consistency in citation coverage in most of the investigated subject areas. Backgroundith classic digital libraries, researchers have no issue with indexing their scientific materials and publications. Citation count is normally used to evaluate author's metric, H Index, journal H Index, impact factor and the international reputation of universities [1-6]. In general, the use of citations for evaluating research quality is related to the assumption that citation counts are one of the tools to measure the credits and recognizes the value, impact, quality, or significance of an author's work [7][8][9][10][11][12].