| Immscible metals system such as molybdenum-silver system has importantapplication prospect in the national economy and national defense construction.Because the heat of reaction of immscible metals system is positive and diffusionbetween them is difficult, directly compositing/jointing immscible metals is difficult.Diffusion between immscible metals can happen in other ways such asamorphous. Based on the above ideas, immscible metals are jointed/compositeddirectly by ways of immscible metal directly bonding and mechanical alloying inwhich solid state amorphization reactions happen. On the basis of the above work, thearticle also puts forward metal super solution theory. The main results are as follows:(1) Diffusion and solid state amorphous reaction happen between molybdenumand silver by way of direct bonding method and the accurate control of bondingtemperature as to realize immscible metals compositing/jointing. And tungsten-silver,molybdenum-copper, niobium-silver et al immscible metals systems can also bedirectly jointed/composited in addition to molybdenum-silver system.(2) Through the metal mechanical alloying method, firstly immscible metalspowders are mixed to the nanoscale by ball milling, then solid state amorphousreaction occurrs in immscible metals during sintering by way of controling thesintering temperature accurately, lastly immscible metals systems can be jointed/composited directly. Influence factors such as ball milling time, ratio of powder andsintering temperature and time are analized and discussed in depth.(3) On the basis of the above results, super dissolution theory is put forward.Silver, copper and other low melting point metals must become a super dissolutionstate in0.9-1.1Tm (Tm refers to metal melting point) and under pressure. This specialstate can dissolve tungsten, molybdenum, niobium, et al which are unable to becomesolid solution to each other, and this solid solubility is very big. Results of HRTEMprove it. |
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