Metal compound material of heat treatment
Intermetallic compound is mainly refers to metal elements, metal elements and metals form compounds, both stoichiometric composition between the elements, but its composition can change within a certain scope again to form a compound for solid solution. Intermetallic compound with its excellent performance, between the metal and ceramic and become a new important branch of structural materials, and get a wide range of applications.
1. Heat treatment
Heat treatment aims to get some kind of orderly structure, in order to improve the plasticity and toughness. Mainly has the following several kinds of treatment.
(1) under the high temperature homogenizing annealing as-cast intermetallic compound general composition segregation and casting stress, high temperature homogenizing annealing is to eliminate casting stress and the alloy elements further spread evenly, processing, which has laid a good foundation for the next step of the process is in commonly 1000 ℃ above lasted for ten hours.
(2) the oil quenching in order to increase the toughness at room temperature of the intermetallic compound, often transform heat into the crystal shape or phase transition temperature, and then into the oil quenching treatment, such as Fe, Al intermetallic compounds of the typical treatment technology for: heated to 1000 ℃, heat preservation and 5 h, then in 700 ℃ oil cooling can be found in the references.
Thermomechanical treatment (3) this is to increase the toughness and intermetallic compounds are the most effective way to handle it, mainly through forging, rolling, extrusion, such as thermal deformation processing, make its organization structure is helpful to increase the toughness of the shift, typical process documents.
Room temperature brittleness of intermetallic compound is a problem of this kind of material used. The composition of the alloy, due to the different processing method and the change of process parameters, the final microstructure and mechanical properties may be far, widely used in the preparation of intermetallic compound thermal mechanical processing technology, adopting this method can get the general processing cannot achieve good cooperate with high strength and high plasticity of the product.
2. The development and application prospects
Intermetallic compound has been used in metal materials, metal matrix strengthening phase. People by changing the types of intermetallic compound, distribution and precipitation state as well as the relative content and so on to achieve the goal of control matrix material performance. Because it has many unique properties, intermetallic compound itself as a kind of new material is being increasingly extensive research and development. Intermetallic compound with high temperature resistant, corrosion resistant performance, become the aviation, aerospace, transportation, chemical industry, machinery and many other industries important structural materials; Because of its many advantages such as sound, light, electricity, magnetic special physical properties and can be used as a semiconductor, magnetic functional materials, hydrogen storage, superconductive, etc. Especially used as ordered intermetallic compound of high temperature structural materials, has a number of good mechanical properties and characteristics of oxidation resistance, corrosion resistance, and high specific strength, because of its long range order atomic arrangement and the co-existence of the metallic bond and covalent bond between atoms, makes it possible both metal plasticity and high temperature strength of the ceramic, and the application prospect of extremely.
However, the brittleness of intermetallic compounds hinders its application. Until the early 80 s, intermetallic compound toughening research two big breakthrough, one is the Japan institute of materials science and springs, etc in the brittleness of polycrystalline Ni3Al joined mass fraction is 0.02% ~ 0.05% of B, make the material toughening, room temperature tensile elongation increased from nearly 0 to 40% ~ 50%; Second, oak ridge national laboratory in the United States found that no plastic Co3V six-party D019 structure, to use some hosting of Ni, Fe, Co, can make its transformation into a face-centered cubic L12 structure, brittle material into a good plastic material. These developments make people see the hope of intermetallic compound high temperature structural materials and prospects, set off a worldwide research boom.
