鈮鎳鋁三元介金屬顆粒強化鋁基複合材料之製備及機械性質

Fabrication and Mechanical Properties of Nb-Ni-Al Ternary Intermetallic Particle-reinforced Al Matrix Composite

林秉毅(Bing-Yih Lin)

指導教授 ： 吳新明

大同大學/工程學院/材料工程學系所/碩士(2011年)

摘要

本實驗是藉由機械合金法，製備鈮鎳鋁三元介金屬相強化鋁基複合材料。實驗第一階段，根據Nb-Ni-Al三元平衡相圖，選取適當的Nb、Ni、Al粉末，以機械合金球磨，並以熱退火處理，分別合成Nb(Al,Ni)2拉夫斯相粉末和NbNi2Al赫斯勒相粉末。經球磨和退火處理粉末以XRD和SEM觀察其相變化和形貌特徵。實驗第二階段，將上述方法合成之拉夫斯相粉末或赫斯勒相粉末與適當比例之鋁粉，經30分鐘機械合金球磨，再將粉末以80 MPa、500 ℃真空熱壓1小時，製成不同含量之拉夫斯相或赫斯勒相強化鋁基複合材料，以探討不同含量之強化相對其微觀結構和機械性質的影響。由實驗結果得知，拉夫斯相和赫斯勒相粉末無法直接藉由機械合金合成必須再分別經過1200 ℃和800 ℃熱退火處理。經退火處理之粉末隨著球磨時間增加，粒徑逐漸減少，且形貌類似球狀。混合粉末因為在熱壓前經過30分鐘球磨，所以塊材晶粒細化，且強化相均勻地分佈在鋁基中。鋁基複合材料隨著強化相加入的體積百分比提升，其硬度上升，但相對密度下降。當拉夫斯或赫斯勒相添加40 vol.%時，硬度分別為259 Hv和273 Hv。

關鍵字

鋁基複合材料 ； 機械合金化 ； 赫斯勒相 ； 拉夫斯相 ； 熱壓

並列摘要

In this study, aluminum matrix composites (AMCs) reinforced by Nb-Ni-Al ternary intermetallic particle was prepared by mechanical alloying. The first phase of this study selects appropriate Nb, Ni, and Al compositions based on the Nb-Ni-Al ternary equilibrium diagram to synthesize Nb(Ni,Al)2 Laves and NbNi2Al Heusler powders by mechanical alloying and subsequent annealing treatment. The phase transformation and morphology characteristics of the as-milled and heat-treated powders were studied by using XRD and SEM. In the second phase, the synthesized Laves phase and Heusler phase powders were, respectively, blended with additional Al powder and subjected to further milling for 30 min and vacuum hot-pressing at 500 ℃, 80 MPa for 1 h to produce AMCs contain different volume fractions of Laves and Heusler strengthening phases. The effect of volume fractions of strengthening phases on microstructures and mechanical properties of AMCs were investigated. The results indicate that Laves phase and Heusler phase powders cannot be synthesized directly from elemental powders by mechanical alloying, but can be obtained after annealing on the as-milled powders for 1 h at 1200 ℃ and 800 ℃, respectively. With the increase of milling time, the particles of the heat-treated powders were decreased in size and revealed spherical morphology. The vacuum hot-pressed bulk composites consolidated from the further milling blended powders exhibit grain refinement in bulk composite as well as the refinement and homogeneity of the strengthening particles, as compared to the bulk composites made from unmilled blended powders. As the strengthening phases increase, the measured hardness of AMCs increases and the relative density decreases. With the addition of 40 vol.% Laves and Heusler phases, the hardness of the bulk composites increases to 259 Hv and 273 Hv, respectively.

並列關鍵字

aluminum matrix composites ； Laves phase ； mechanical alloying ； Heusler phase ； hot-pressing

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