The microstructural evolution and precipitation location of the secondary phase of an as-cast Ti-25 V-15 Cr-0.3 Si titanium alloy were investigated via isothermal compression experiments and heat treatment. The averag...The microstructural evolution and precipitation location of the secondary phase of an as-cast Ti-25 V-15 Cr-0.3 Si titanium alloy were investigated via isothermal compression experiments and heat treatment. The average aspect（length-to-width） ratio, average area and size of the grains at different heat treatment temperatures and holding time were analyzed and the effects of deformation and annealing time on the grain area and size were considered. It was found that the grain size was strongly influenced by the height reduction and holding time. Grain growth was significant when annealing time increased from 10 min to 2 h at 950 °C and height reduction of 30%; however, grain growth was minimal at annealing time between 2 and 4 h. Many dispersion particles were observed to form in continuous chains; the precipitation location was confirmed to be along initial grain boundaries, and the dispersion particles were identified to be Ti5 Si3 phase by TEM.展开更多
Often masonry walls of historical buildings are subject to rising damp effects due to capillary or rain infiltrations. In the time, their cyclic action produces decay and delamination of historical plasters. An experi...Often masonry walls of historical buildings are subject to rising damp effects due to capillary or rain infiltrations. In the time, their cyclic action produces decay and delamination of historical plasters. An experimental laboratory procedure for the pre-qualification of repair mortars is described. Long-term plaster delamination frequently occurs because of the mechanical incompatibility of new repair mortars. The tested mortars are suitable for new dehumidified plasters applied to historical masonry walls. Compression static tests were carried out on composite specimens stSone block-repair mortar, which specific geometry can test the de-bonding process of mortar in adherence with historical masonry structure. A numerical simulation based on the cohesive crack model was used to follow the experimental data, in order to describe the evolutionary phenomenon of de-bonding as a function of a small number of parameters. This method supplies useful indication for selecting the product that is best in keeping with the mechanical characteristics of the historical material, thereby avoiding errors associated with materials that are not mechanically compatible. Currently, the methodology is being used at Sacro Monte di Varallo Special Natural Reserve （UNESCO heritage site） in Piedmont （Italy）.展开更多
基金Projects(51501122,51604181) supported by the National Natural Science Foundation of ChinaProject(20172009) supported by the Postdoctoral Sustentation Fund of Taiyuan University of Science and Technology,China+3 种基金Project(20132016) supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProject(201501004-8) supported by the Jincheng Science and Technology Plan Project,ChinaProject(U1510131) supported by NSFC-Shanxi Coal-based Low-carbon United Fund and"Shanxi Young Scholars"Program,ChinaProject(201603D121010) supported by Key R&D Program of Shanxi Province,China
文摘The microstructural evolution and precipitation location of the secondary phase of an as-cast Ti-25 V-15 Cr-0.3 Si titanium alloy were investigated via isothermal compression experiments and heat treatment. The average aspect（length-to-width） ratio, average area and size of the grains at different heat treatment temperatures and holding time were analyzed and the effects of deformation and annealing time on the grain area and size were considered. It was found that the grain size was strongly influenced by the height reduction and holding time. Grain growth was significant when annealing time increased from 10 min to 2 h at 950 °C and height reduction of 30%; however, grain growth was minimal at annealing time between 2 and 4 h. Many dispersion particles were observed to form in continuous chains; the precipitation location was confirmed to be along initial grain boundaries, and the dispersion particles were identified to be Ti5 Si3 phase by TEM.
文摘Often masonry walls of historical buildings are subject to rising damp effects due to capillary or rain infiltrations. In the time, their cyclic action produces decay and delamination of historical plasters. An experimental laboratory procedure for the pre-qualification of repair mortars is described. Long-term plaster delamination frequently occurs because of the mechanical incompatibility of new repair mortars. The tested mortars are suitable for new dehumidified plasters applied to historical masonry walls. Compression static tests were carried out on composite specimens stSone block-repair mortar, which specific geometry can test the de-bonding process of mortar in adherence with historical masonry structure. A numerical simulation based on the cohesive crack model was used to follow the experimental data, in order to describe the evolutionary phenomenon of de-bonding as a function of a small number of parameters. This method supplies useful indication for selecting the product that is best in keeping with the mechanical characteristics of the historical material, thereby avoiding errors associated with materials that are not mechanically compatible. Currently, the methodology is being used at Sacro Monte di Varallo Special Natural Reserve （UNESCO heritage site） in Piedmont （Italy）.
