激光重熔处理对铸态Zn-27%Al合金的组织和性能的影响

经激光表面重熔处理后高铝锌基铸态Ｚｎ－２７％Ａｌ合金的表层组织结构和性能均发生了较大的变化。表层组织根据其组织形态特征可分为非树枝状晶区、树枝状晶区和半熔化区三层。与激光处理前的相比，在Ｘ射线衍射谱上个η－Ｚｎ相衍射强度降低，α－Ａｌ相衍射峰出现边带效应。表层硬度和耐磨性由于组织细化而分别提高了约１５％和２６％。若提高激光加热功率，硬化层深度随之增加。

Mg对Zn—27%Al合金组织转变的价电子结构分析

本文首先分析了 ZA27合金的铸态组织,指出其组织组成相为α、β和η。α和β相在固态下将发生一系列转变,η相仅发生长大、粗化和粒化过程。依据“固体与分子经验电子理论”,建立 Al—Zn 二元和 Al—Zn—Mg 三元α(或β)面心立方晶胞的价电子键络模型。计算结果表明:Mg 原子无论是位于面心立方晶胞的面心或是顶角位置,都将加强面心立方晶胞的键络,提高α(或β)晶胞的稳定性,从微观电子结构解释了 Mg 强化合金组织的本质。

Fabrication of sintered Zn-27%Al and comparison of its tribological behavior with cast alloy

High quality Zn base powder with low oxygen content, fine particle size and fine microstructure can be obtained by gas atomization using nitrogen. Cast and sintered Zn 27%Al alloys (ZMJ) were prepared. Tribological behaviors of the cast and sintered alloys under lubricated and non lubricated conditions were studied and compared. Worn surfaces and microstructures of these alloys were examined. Results indicate that although the strength of the sintered alloy is considerably less than that of the cast alloy, the sintered alloy has a better wear resistance. The fine microstructure obtained by rapid solidification is beneficial to the wear resisting property. The wear volume of sintered ZMJ is only 36% and 59% of the wear volume that found in cast ZMJ under non lubricated and lubricated conditions, respectively. For lubricated wear test, abrasive wear is the major wear mechanism and for non lubricated wear test, oxidation wear and adhesive wear are the major wear mechanisms.

铸造Zn－27％Al合金调幅分解特征分析

利用Ｘ射线衍射和ＴＥＭ对Ｚｎ－２７％Ａｌ（ＺＡ２７）合金铸态组织的微观结构进行研究，发现存在调幅分解。其特征为Ｘ射线图谱上出现边带效应，ＴＥＭ选区衍射时出现二次衍射斑，调幅分解是沿＜１１１＞ａ（β）晶向优先发生，ＴＥＭ组织中有“类织物”结构。调幅分解产物在时效时长大并向稳定的α、η组织转变。