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发展了在多次重复的冷却速率条件下产生猝冷金相显微组织的一种新的处理工艺。通过高能量密度的连续波激光束的快速扫描,在金属材料表面产生一薄层熔化层。很高的能量传递速率,促使局部表面以极高的速率熔化,即所吸收能量的主要部分是用于熔化材料,而耗于加热固相次表面的只有很少的一部分能量。这样,在材料表面熔化一薄层的同时保持冷基质性质以使熔化层在激光扫描之后产生快速淬火。对纯镍的计算表明:2.5×10~(-3)毫米厚的熔化层的冷却速率可达5×10~8开氏温度/秒,而2.5×10~(-2)毫米厚的熔化层的冷却速率可达5×10~6开氏温度/秒。快速淬火的重要性在于:在固相中可保留(或几乎保留)液相的无比均匀性,这种组织既可就此使用或再经转变可产生其它所期望的性能。这种处理工艺叫做“激光上釉(LaserGlazing)”。已经证明这种处理能在大块金属表面上产生许多种新奇的有趣的金相显微组织。激光上釉可在大块基质上产生低熔点共晶池成分的非晶态表面层。在其它组成上分布着固溶相。这些可以分解成微细的固态的各种多相显微组织。这样的组成是新型的弥散强化合金的候选者。在含较多第二相的组成中,得到了极细的纤维状共晶显徼组织。已由实验证实:对多种单晶基质材料,在不恫取向上存在强烈的附晶生长(外延生长)倾向。激光上釉(以及激光表面合金化,上釉后热处理,和/或形变处理)可作为产生许多新奇表面显微组织及性能的一种灵活手段。虽然目前首先把它用于材料的表面处理工艺,也可能通过接续的层层上釉的迭加来处理整体材料。
A new process has been developed for producing microstructures of quenched metallurgy at repeated cooling rates. A fast sweep of a continuous-wave laser beam of high energy density produces a thin layer of melted layer on the surface of the metal material. The high energy transfer rate causes the local surface to melt at an extremely high rate, ie the major part of the absorbed energy is used to melt the material and consume only a small fraction of the energy to heat the solid secondary surface. In this way, a thin layer is melted on the surface of the material while maintaining cold matrix properties so that the melted layer produces a rapid quench after laser scanning. The calculation of pure nickel shows that the cooling rate of 2.5 × 10 ~ (-3) mm thick melt layer can reach 5 × 10-8 Kelvin / second, while the thickness of 2.5 × 10 -2 mm thick melt layer The cooling rate of up to 5 × 10 ~ 6 Kelvin / sec. The importance of rapid quenching is that the unparalleled homogeneity of the liquid phase can be retained (or nearly retained) in the solid phase and that this tissue can be used with this or re-transformed to produce other desired properties. This process is called “LaserGlazing”. This process has proven to produce many novel and interesting metallurgical microstructures on large metal surfaces. Laser glazing produces an amorphous surface layer of low melting point eutectic cell composition on a bulk substrate. In other composition distribution of the solid solution phase. These can be decomposed into fine solid multi-phase microstructure. Such a composition is a new candidate for dispersion strengthened alloys. In the composition with more second phase, a very fine fibrous eutectic xantha was obtained. It has been experimentally confirmed that there is a strong tendency for apatite growth (epitaxial growth) in a variety of single crystal host materials. Laser glazing (as well as laser surface alloying, post-enamel heat treatment, and / or deformation treatment) can be used as a flexible means of producing many novel surface microstructures and properties. Although it is currently used primarily for the surface treatment of materials, it is also possible to process the bulk material by successive layers of glazing.