Monitoring and assessment of monuments of cultural heritage is just a small part of all measures necessary for their protection and preservation. Many of these monuments are built of stone and the binder used to bond ...Monitoring and assessment of monuments of cultural heritage is just a small part of all measures necessary for their protection and preservation. Many of these monuments are built of stone and the binder used to bond the construction blocks after a lengthy period of time loses its properties. The loss of binding material or changes in its properties substantially endangers the stability of the monuments thus constituting a menace not only for the visitors, but also for the conservation work. One of such monuments is the Step Pyramid of Djoser in Egypt. In this pyramid different artificial compositions are used as binder and its application in different areas of the pyramid is uneven and almost undistinguishable. Currently it is only possible to appraise the state of preservation of the mortar as a result of weathering process. This research allows identifying up to six weathering types and their intensities. This typology was developed on several sample areas verifying its validity in situ. Since there is no possibility to carry out direct instrumental measurements or take any samples, the classification developed is just empirical and not general. However, it provides relevant support for the development of conservation plans.展开更多
As human improve their ability to fabricate materials, alloys have evolved from simple to complex compositions, accordingly improving functions and performances,promoting the advancements of human civilization. In rec...As human improve their ability to fabricate materials, alloys have evolved from simple to complex compositions, accordingly improving functions and performances,promoting the advancements of human civilization. In recent years, high-entropy alloys（HEAs） have attracted tremendous attention in various fields. With multiple principal components, they inherently possess unique microstructures and many impressive properties, such as high strength and hardness, excellent corrosion resistance, thermal stability, fatigue,fracture, and irradiation resistance, in terms of which they overwhelm the traditional alloys. All these properties have endowed HEAs with many promising potential applications.An in-depth understanding of the essence of HEAs is important to further developing numerous HEAs with better properties and performance in the future. In this paper, we review the recent development of HEAs, and summarize their preparation methods, composition design, phase formation and microstructures, various properties, and modeling and simulation calculations. In addition, the future trends and prospects of HEAs are put forward.展开更多
文摘Monitoring and assessment of monuments of cultural heritage is just a small part of all measures necessary for their protection and preservation. Many of these monuments are built of stone and the binder used to bond the construction blocks after a lengthy period of time loses its properties. The loss of binding material or changes in its properties substantially endangers the stability of the monuments thus constituting a menace not only for the visitors, but also for the conservation work. One of such monuments is the Step Pyramid of Djoser in Egypt. In this pyramid different artificial compositions are used as binder and its application in different areas of the pyramid is uneven and almost undistinguishable. Currently it is only possible to appraise the state of preservation of the mortar as a result of weathering process. This research allows identifying up to six weathering types and their intensities. This typology was developed on several sample areas verifying its validity in situ. Since there is no possibility to carry out direct instrumental measurements or take any samples, the classification developed is just empirical and not general. However, it provides relevant support for the development of conservation plans.
基金supported by the National Natural Science Foundation of China (51471025 and 51671020)
文摘As human improve their ability to fabricate materials, alloys have evolved from simple to complex compositions, accordingly improving functions and performances,promoting the advancements of human civilization. In recent years, high-entropy alloys（HEAs） have attracted tremendous attention in various fields. With multiple principal components, they inherently possess unique microstructures and many impressive properties, such as high strength and hardness, excellent corrosion resistance, thermal stability, fatigue,fracture, and irradiation resistance, in terms of which they overwhelm the traditional alloys. All these properties have endowed HEAs with many promising potential applications.An in-depth understanding of the essence of HEAs is important to further developing numerous HEAs with better properties and performance in the future. In this paper, we review the recent development of HEAs, and summarize their preparation methods, composition design, phase formation and microstructures, various properties, and modeling and simulation calculations. In addition, the future trends and prospects of HEAs are put forward.
