Three-phase Reaction Type Changing In Systems Ti-Ru-Ir And Zr-Ru-Ir

Abstract:

The change of congruent crystallization L->D+Ru (D=TiIr3) to incongruent one L+D->Ru has been found in system Ti-Ru-Ir . Analogous change of crystallization type from incongruent L+D->F to congruent L->D+F (D=ZrIr3, F=ZrIr2) has a place in system Zr-Ru-Ir . The same type of eutectoid-peritectoid transformations exists in other metallic systems . Special surface corresponds to changing of phase transformation type in 3-phase regions . At this moment a 3-phase reaction becomes ad interim as 2-phase one in presence of third phase. Passive role of this phase f means that the transformation of its mass portion changes the sign: dm(f)=0. Conditions dm(f)=0 for every of three phases give in any 3-phase region 3 virtual 2-phase surfaces. Every of them can be real at concrete temperature-concentration condition. 2-phase surface is also a ruled one. As for T-x-y-z diagrams, 3-phase region L+a+b have boundaries in a form of the ruled hyper-surfaces with horizontal generated segment, which slides on 2 from 3 directing surfaces which form a phase region. There is the isothermal curve at temperature T on every of 3 directing surfaces. If these 3 isotherms are given by one parameter t then 3 points at the same 0 < t < 1 on every isotherm produce the triangle Lab. In dependence on temperature-concentration conditions it is possible that this triangle has a line which belongs to the hyper-surface dm(f)=0, where f=L, a, b. Changing the parameter t from 0 to 1 forms the isothermal at T ruled surface. The ruled hyper-surface with horizontal generating line is formed from such ruled surfaces at different T. This hyper-surface corresponds to 2-phase reaction with indifferent third phase too.

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