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本文从44个缓冷和淬炼Mn-Ga合金摄取了德拜·谢乐照相,并配合了在富Ga部分的差热分析,初步画出了这个系统的相图。 这个系统除纯Ga外共有十个相。Mn在Ga中的固溶度是几乎无可觉察的。α相是Ga在α-Mn中的原固溶体,在室温的固溶度为1.95at％Ga。β相在室温的均匀范围为8.6—19.2at％Ga,这是β-Mn结构,因此可看作是β-Mn的固溶体,由于Ga原子无规地替代了部分Mn原子而这个结构得在室温稳定存在。 γ相可分成γ_1,γ_2,γ_3,三部分,γ_1是面心立方结构,γ_2是面心四方结构,γ_3是有序的面心四方结构,与Cu-Au系中的 CuAuⅠ同型。在室温下稳定的是γ_3,均匀范围为37—45at％Ga,而在高温稳定的却总是γ_1。从γ_1变到γ_2,再从γ_2变到γ_3的变化是二级相变。有序度随Ga含量的递增而递增,随温度的递升而递降。整个γ相可看作是γ-Mn的固溶体,γ-Mn本身是不可能用淬炼的办法在室温获得的。 δ相只存在于高温,可看作是δ-Mn的固溶体。由于Ga原子替代了部分Mn原子,因而δ一Mn结构产生了畸变而有序化。 ε相是有序的六角密堆积结构,每个晶胞含8个原子,它是在约820℃从γ相同成份地转变而成的,在室温的均匀范围估计为 27一30 at％Ga。 η相在室温约50—60at％Ga处有一宽广的均匀范围。从520到600℃,它经历一多型性变
In this paper, Debye Xerole photography was taken from 44 slow-cooling and quenched Mn-Ga alloys and the phase diagram of this system was preliminarily drawn in accordance with the differential thermal analysis of the Ga-rich part. This system has ten phases except pure Ga. The solid solubility of Mn in Ga is almost unobservable. The α phase is an original solid solution of Ga in α-Mn and has a solid solubility of 1.95 at% Ga at room temperature. The uniform range of β phase at room temperature is 8.6-19.2 at% Ga, which is a β-Mn structure and therefore can be regarded as a solid solution of β-Mn. Since Ga atom randomly replaces a part of Mn atoms, this structure is at room temperature Stable existence. γ phase can be divided into γ_1, γ_2, γ_3, three parts, γ_1 is face-centered cubic structure, γ_2 is face-centered tetragonal structure, and γ_3 is ordered face-centered tetragonal structure, which is the same as CuAuⅠ in Cu-Au series. It is γ_3 stable at room temperature, with an even range of 37-45 at% Ga, while it is always γ_1 at high temperatures. The change from γ_1 to γ_2 and then from γ_2 to γ_3 is the second-order phase transition. The degree of order increases with the increase of Ga content, and decreases with the increase of temperature. The whole γ phase can be regarded as a solid solution of γ-Mn, and γ-Mn itself can not be obtained by a quenching method at room temperature. The δ phase exists only at high temperature and can be regarded as a solid solution of δ-Mn. Since Ga atoms replace part of the Mn atoms, the δ-Mn structure is distorted and ordered. The ε phase is an ordered hexagonal close packed structure with 8 atoms per unit cell, which is transformed from the same γ composition at about 820 ° C. The homogeneous range at room temperature is estimated to be 27 to 30 at% Ga. The η phase has a broad, uniform range at about 50-60 at% Ga at room temperature. From 520 to 600 ° C, it undergoes a polymorphic change