W_(45)Cu_(55),Cr_(65)Cu_(35),and Cr_(32)W_(14)Cu_(54)alloys were obtained in order to study the mechanism of“smart response”of the structure of these alloys when using them as arc-resistant circuit-breakers.These al...W_(45)Cu_(55),Cr_(65)Cu_(35),and Cr_(32)W_(14)Cu_(54)alloys were obtained in order to study the mechanism of“smart response”of the structure of these alloys when using them as arc-resistant circuit-breakers.These alloys differ from industrial ones with frameless packing of Cr and W phases in the copper matrix.The alloy production method is based on the infiltration of copper melt into a mixture of non-compacted Cr and W powders under vibration exposure(80 Hz).The research results show an increase in the arc resistance of contacts when changing from“frame”packing of W to“frameless,”as well as the decisive role of Cr in the processes of self-dispersion of arc-resistant phases and passivation of W and Cu.Based on the obtained results,conclusions are drawn about the advantage of frameless packing of arc-resistant phases in copper and the reasons for the“smart behavior”of the structure of Cr-containing contacts in response to functional loads in the presence of oxygen and an inert atmosphere.展开更多
The first wall of the fusion reactor is a plasma-facing component and is a key link to maintain the integrity of structure during thermal shock induced by plasma disruptions. Be and W/Cu functionally graded materials ...The first wall of the fusion reactor is a plasma-facing component and is a key link to maintain the integrity of structure during thermal shock induced by plasma disruptions. Be and W/Cu functionally graded materials are two kinds of important plas- ma-facing materials （PFM） of first wall in fusion reactor currently. Previous researches seldom comparatively evaluated the normal servicing and heat shock resistance performance of first walls with those two kinds of PFMs. And also there lacks cou- pled thermal/mechanical analysis on the heat shock process in consideration of multiple thermal/mechanical phenomena, such as material melting, solidification, evaporation, etc., which is significant to further understand the heat shock damage mecha- nism of the first wall with different PFMs. With the aim of learning more detailed mechanical mechanism of thermal shock damage and then improving the thermal shock resistance performance of different first wall designs, the coupled ther- mal/mechanical response of two typical ITER-like first walls with PFM of Be and functionally graded W-Cu respectively un- der the heat shock of 1 2 GW/m2 are computed by the finite element method. Special considerations of elastic-plastic defor- mation, material melting, and solidification are included in numerical models and methods. The mechanical response behaviors of different structures and materials under the normal servicing operation as well as plasma disruption conditions are analyzed and investigated comparatively. The results reveal that heat is mainly deposited on the PFM layer in thc high energy shock pulse induced by plasma disruptions, resulting in complex thermal stress change as well as mechanical itTeversible damage of thermal elastic and plastic expansion, contraction and yielding. Compared with the first wall with Be PFM, which mitigates the damages from heat shock at most only in the PFM layer with cost of whole PFM layer plastic yielding, the first wall with graded W-Cu PFM is demonstrated to be possessed both of higher heat shock resistance performance and normal servicing performance, provided its material gradient and cooling capacity are well optimized under practical loading conditions.展开更多
文摘W_(45)Cu_(55),Cr_(65)Cu_(35),and Cr_(32)W_(14)Cu_(54)alloys were obtained in order to study the mechanism of“smart response”of the structure of these alloys when using them as arc-resistant circuit-breakers.These alloys differ from industrial ones with frameless packing of Cr and W phases in the copper matrix.The alloy production method is based on the infiltration of copper melt into a mixture of non-compacted Cr and W powders under vibration exposure(80 Hz).The research results show an increase in the arc resistance of contacts when changing from“frame”packing of W to“frameless,”as well as the decisive role of Cr in the processes of self-dispersion of arc-resistant phases and passivation of W and Cu.Based on the obtained results,conclusions are drawn about the advantage of frameless packing of arc-resistant phases in copper and the reasons for the“smart behavior”of the structure of Cr-containing contacts in response to functional loads in the presence of oxygen and an inert atmosphere.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Grant Nos.2015GB121007&2013GB113004)
文摘The first wall of the fusion reactor is a plasma-facing component and is a key link to maintain the integrity of structure during thermal shock induced by plasma disruptions. Be and W/Cu functionally graded materials are two kinds of important plas- ma-facing materials （PFM） of first wall in fusion reactor currently. Previous researches seldom comparatively evaluated the normal servicing and heat shock resistance performance of first walls with those two kinds of PFMs. And also there lacks cou- pled thermal/mechanical analysis on the heat shock process in consideration of multiple thermal/mechanical phenomena, such as material melting, solidification, evaporation, etc., which is significant to further understand the heat shock damage mecha- nism of the first wall with different PFMs. With the aim of learning more detailed mechanical mechanism of thermal shock damage and then improving the thermal shock resistance performance of different first wall designs, the coupled ther- mal/mechanical response of two typical ITER-like first walls with PFM of Be and functionally graded W-Cu respectively un- der the heat shock of 1 2 GW/m2 are computed by the finite element method. Special considerations of elastic-plastic defor- mation, material melting, and solidification are included in numerical models and methods. The mechanical response behaviors of different structures and materials under the normal servicing operation as well as plasma disruption conditions are analyzed and investigated comparatively. The results reveal that heat is mainly deposited on the PFM layer in thc high energy shock pulse induced by plasma disruptions, resulting in complex thermal stress change as well as mechanical itTeversible damage of thermal elastic and plastic expansion, contraction and yielding. Compared with the first wall with Be PFM, which mitigates the damages from heat shock at most only in the PFM layer with cost of whole PFM layer plastic yielding, the first wall with graded W-Cu PFM is demonstrated to be possessed both of higher heat shock resistance performance and normal servicing performance, provided its material gradient and cooling capacity are well optimized under practical loading conditions.
