In wear protection, cobalt-base or nickel-base materials are very often used for coatings in order to increase the functionality and service life of components. These materials such as stellite, the nickel-base alloy Colmonoy 56 or Tribaloy T400 are characterized by a high resistance to abrasion, adhesion as well as excellent corrosion resistance even at higher temperatures. Given the criticality of cobalt and partly also nickel, it is necessary to look for more sustainable alternatives to be used in wear protection. One possibility is to further develop iron-base materials so that they can be used in wear protection to prevent both abrasion and adhesion. In this context, sufficient corrosion resistance is desirable. This paper will elaborate on the development of a novel intermetallic iron-base hard alloy.
{"title":"Characterization and comparison of cobalt-base and nickel-base alloys with iron-base intermetallic hard alloys used in wear protection","authors":"S. Friederichs, S. Lorenz","doi":"10.1515/pm-2024-0012","DOIUrl":"https://doi.org/10.1515/pm-2024-0012","url":null,"abstract":"\u0000 In wear protection, cobalt-base or nickel-base materials are very often used for coatings in order to increase the functionality and service life of components. These materials such as stellite, the nickel-base alloy Colmonoy 56 or Tribaloy T400 are characterized by a high resistance to abrasion, adhesion as well as excellent corrosion resistance even at higher temperatures.\u0000 Given the criticality of cobalt and partly also nickel, it is necessary to look for more sustainable alternatives to be used in wear protection. One possibility is to further develop iron-base materials so that they can be used in wear protection to prevent both abrasion and adhesion. In this context, sufficient corrosion resistance is desirable. This paper will elaborate on the development of a novel intermetallic iron-base hard alloy.","PeriodicalId":508095,"journal":{"name":"Practical Metallography","volume":"150 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140446545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this contribution, a fabrication problem is discussed, related to Laser Beam Welding (LBW). Strictly speaking, the case study presented herein does not constitute a failure as such, since the subject components never made it to component service. In the narrow sense of the word, a component failure happens if and when a part does no longer serve its proper function. This is definitely not the case in the study put forward in this paper. However, one could argue that a product that cannot be marketed for lack of certain properties, or because of certain shortcomings, is rendered worthless for the manufacturer and this, in turn, could be considered a failure. In this case study, the issue of discoloration on the surfaces of welded austenitic stainless steel is discussed. This is a well-known and well-researched fabrication problem. Dependent upon service conditions of affected parts, discoloration might be detrimental to the normally outstanding corrosion resistance of this class of high-alloy steels.
{"title":"Discoloration on Laser Welds of AISI 321 Tubes","authors":"A. Neidel, J. Rockel, S. Riesenbeck","doi":"10.1515/pm-2024-0015","DOIUrl":"https://doi.org/10.1515/pm-2024-0015","url":null,"abstract":"\u0000 In this contribution, a fabrication problem is discussed, related to Laser Beam Welding (LBW). Strictly speaking, the case study presented herein does not constitute a failure as such, since the subject components never made it to component service. In the narrow sense of the word, a component failure happens if and when a part does no longer serve its proper function. This is definitely not the case in the study put forward in this paper. However, one could argue that a product that cannot be marketed for lack of certain properties, or because of certain shortcomings, is rendered worthless for the manufacturer and this, in turn, could be considered a failure. In this case study, the issue of discoloration on the surfaces of welded austenitic stainless steel is discussed. This is a well-known and well-researched fabrication problem. Dependent upon service conditions of affected parts, discoloration might be detrimental to the normally outstanding corrosion resistance of this class of high-alloy steels.","PeriodicalId":508095,"journal":{"name":"Practical Metallography","volume":"194 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140448423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High entropy alloys (HEA) represent a relatively new class of materials with promising properties for various applications. In recent years, these alloys have received considerable attention as potential heterogeneous catalysts in chemical and electrochemical reactions. Their enhanced catalytic activity is controlled by chemical composition, surface atomic coordination, electronic configuration and degree of microstructural metastability. Single-phase HEAs are of particular importance, because they possess a uniform microstructure that is useful for designing and prediction of mechanical and potential functional properties. The cooling rate has a significant impact on the formation of the microstructure, affecting the size of grains, as well as distribution and composition of precipitates and phases that are being formed during solidification. The influence of different cooling rates on the microstructure of the alloy Ag20Pd20Pt20Cu20Ni20 was studied in our research work. The microstructure and phase constituents were characterised by Scanning Electron Microscopy and X-ray Diffraction. Liquid phase separation with a consequential monotectic reaction resulted in an anomalous multiphase cast microstructure. With an increase in the cooling rate using the melt spinning technique, the number of formed phases and the size of the grains decreased and the high entropy supersaturated solid solution was attained, as the atoms in the alloy did not have enough time to diffuse and to rearrange themselves into a stable, ordered structure. It was also confirmed that higher cooling rates cause severe lattice distortion and create coordinatively unsaturated sites at the surface which are essential for the bonding and activation of the reactants and therefore improve the potential catalytic properties of the Ag20Pd20Pt20Cu20Ni20 alloy significantly.
高熵合金（HEA）是一类相对较新的材料，在各种应用中具有良好的性能。近年来，这些合金作为化学和电化学反应中潜在的异质催化剂受到了广泛关注。其催化活性的增强受化学成分、表面原子配位、电子构型和微结构易变程度的控制。单相 HEA 尤为重要，因为它们具有均匀的微观结构，有助于设计和预测机械性能和潜在的功能特性。冷却速率对微观结构的形成有重大影响，会影响晶粒大小以及凝固过程中形成的析出物和相的分布和组成。我们的研究工作研究了不同冷却速率对 Ag20Pd20Pt20Cu20Ni20 合金微观结构的影响。通过扫描电子显微镜和 X 射线衍射法对微观结构和相组成进行了表征。液相分离和随之而来的单共晶反应导致了异常的多相铸造微观结构。由于合金中的原子没有足够的时间进行扩散并重新排列成稳定有序的结构，因此使用熔融纺丝技术提高冷却速度后，形成的相的数量和晶粒的尺寸都有所减小，达到了高熵过饱和固溶体。研究还证实，较高的冷却速率会导致严重的晶格畸变，并在表面形成配位不饱和位点，这对于反应物的键合和活化至关重要，因此可显著改善 Ag20Pd20Pt20Cu20Ni20 合金的潜在催化特性。
{"title":"Microstructural analysis of the cast and melt-spun high entropy noble alloy Ag20Pd20Pt20Cu20Ni20","authors":"L. Simić, A. Kneissl, I. Anžel","doi":"10.1515/pm-2024-0014","DOIUrl":"https://doi.org/10.1515/pm-2024-0014","url":null,"abstract":"\u0000 High entropy alloys (HEA) represent a relatively new class of materials with promising properties for various applications. In recent years, these alloys have received considerable attention as potential heterogeneous catalysts in chemical and electrochemical reactions. Their enhanced catalytic activity is controlled by chemical composition, surface atomic coordination, electronic configuration and degree of microstructural metastability. Single-phase HEAs are of particular importance, because they possess a uniform microstructure that is useful for designing and prediction of mechanical and potential functional properties. The cooling rate has a significant impact on the formation of the microstructure, affecting the size of grains, as well as distribution and composition of precipitates and phases that are being formed during solidification. The influence of different cooling rates on the microstructure of the alloy Ag20Pd20Pt20Cu20Ni20 was studied in our research work. The microstructure and phase constituents were characterised by Scanning Electron Microscopy and X-ray Diffraction. Liquid phase separation with a consequential monotectic reaction resulted in an anomalous multiphase cast microstructure. With an increase in the cooling rate using the melt spinning technique, the number of formed phases and the size of the grains decreased and the high entropy supersaturated solid solution was attained, as the atoms in the alloy did not have enough time to diffuse and to rearrange themselves into a stable, ordered structure. It was also confirmed that higher cooling rates cause severe lattice distortion and create coordinatively unsaturated sites at the surface which are essential for the bonding and activation of the reactants and therefore improve the potential catalytic properties of the Ag20Pd20Pt20Cu20Ni20 alloy significantly.","PeriodicalId":508095,"journal":{"name":"Practical Metallography","volume":"69 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140448661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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