Cu-Ti合金时效早期相变规律的研究

Investigation on Transformation of the Early Stage of Aging in Cu Ti Alloys

本文应用透射电子显微镜、Ｘ射线衍射等手段研究了Ｃｕ－Ｔｉ合金时效相变早期的分解过程。研究表明，过饱和的Ｃｕ－Ｔｉ合金固溶体可能首先发生的是溶质原子的短程有序化，然后通过调幅分解机理分解为贫、富溶质区，富溶质区原子进行长程有序排列，形成Ｄ１ａ型的Ｃｕ４Ｔｉ有序相。同时应用图形热力学对Ｃｕ－Ｔｉ合金分解过程中调幅分解与有序化共存的现象进行了解释。Ｃｕ－Ｔｉ合金时效过程中显微硬度的变化出现了双峰现象，第一个峰值的出现与位错密度有关。

In this paper,an investigation on transformation of the early stage of aging in Cu Ti alloys has been conducted by means of transmission electron microscope,X ray diffraction and etc.It concludes that a supersaturated Cu Ti solution decomposes after spinodal ordering with solute atoms′ short range migration into Ti depleted and enriched regions,followed by and concomitant with the long range ordering reaction by which a coherent metastable ordered Cu 4Ti with D 1a type structure has been formed.The coexisting of spinodal and ordering in Cu Ti alloys has been interpreted according to the graphic thermodynamics.There are two hardness peak in curves of the microhardness variation with aging time.The variation of dislocation density and modulated wavelength is attributed to the first peak.The reason for the second peak is that a coherent metastable ordered Cu 4Ti is forming.