A method for preparing in situ MgSi particle reinforced metal matrix composite

Abstract

A method for preparing in situ MgSi particle reinforced metal matrix composite comprises the following steps: feeding 10-60% in situ Mg2Si-Mg or Mg2Si-Al raw material, based on particle volume percentage, into the a furnace under the gas protection condition; keeping the temperature for 5-20 min between the solidus temperature and the liquidus temperature to obtain a semisolid intermediate; melting the matrix alloy under the superheat degree of being 100-300 DEG C and the gas protection condition, and then keeping the temperature for 5-20 min to maintain the matrix alloy to be in the temperature of 0-30 DEG C below the liquidus temperature; adding the semisolid intermediate while stirring for 1-20 min at the stirring speed of 100-600 rew / min, rising the temperature to the superheat degree of 10-100 DEG C, continuously stirring for 1-20 min at the stirring speed of 100-300 rew / min, and then standing for a while; rheocasting the prepared alloy flux with the superheat degree of 10-100 DEG C to obtain a semisolid composite slurry, and finally press forming. The composite primary crystal prepared by the invention is fine and in spherical shape, the Mg2Si particle as reinforcement phase is fine and uniform in distribution. Accordingly, the oxidation during the composite preparation can be effectively reduced, and the near net shape forming of the composite can be achieved.

Description

technical field [0001] The invention belongs to the field of metal matrix composite materials, and relates to an in-situ self-generated Mg 2 A method for the preparation of Si particle reinforced metal matrix composites, especially a method for preparing in situ self-generated Mg by remelting isothermal treatment and rheocasting 2 8i Process for particle reinforced aluminum alloys, magnesium alloys and zinc-aluminum alloy matrix composites. technical background [0002] Particle-reinforced metal matrix composites have the characteristics of simple preparation process, low cost, easy final molding, and easy machining, and have become one of the research hotspots of scientific researchers. The preparation methods of particle-reinforced metal matrix composites can be divided into two categories: external and in-situ synthesis methods from the way the reinforcement is introduced into the matrix. Among them, the in situ synthesis has the advantages of small reinforcing phase, u...

AI Technical Summary

Problems solved by technology

Chinese patent 200480029270.X describes a method using thixotropic molding to prepare Mg with a volume content of at least 2% 2 Si magnesium-based composite materials, but this method requires a special thixoforming machine, which is very expensive and greatly increases the preparation cost of this type of composite material

[0004] in situ Mg 2 Si particle-reinforced metal matrix composites have attracted increasing attention from scholars at home and abroad, but the current research still has the following shortcomings: (1) Although the existing methods or processes can well control the Mg 2 Si size and distribution, but Mg 2 The form of Si is still granular, mostly sharp-edged, splitting the matrix

Therefore, the current research results have not fundamentally solved the brittleness of this material; (2) the current research focus is only on the Mg 2 The modification of Si, but the matrix structure is usually a conventional structure, which is not conducive to improving the plasticity of the composite material. It is very necessary to control the size and shape of the matrix grains