粉末冶金鋁合金燒結致密化過程

邱婷婷; 吳茂; 杜智淵; 曲選輝

doi:10.13374/j.issn2095-9389.2018.09.008

粉末冶金鋁合金燒結致密化過程

doi: 10.13374/j.issn2095-9389.2018.09.008

邱婷婷¹,
吳茂^1,2,3, ,,
杜智淵¹,
曲選輝^1,2,3

1) 北京科技大學新材料技術研究院, 北京 100083
2) 現代交通金屬材料與加工技術北京實驗室, 北京 100083
3) 先進粉末冶金材料與技術北京市重點實驗室, 北京 100083

基金項目:

新金屬材料國家重點實驗室自主課題資助項目(2016Z-24)

國家自然科學基金資助項目(51774036)

詳細信息

中圖分類號: TF124
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出版歷程
- 收稿日期: 2018-04-11

Sintering densification process of powder metallurgy aluminum alloy

QIU Ting-ting¹,
WU Mao^{1,2,3
, ,},
DU Zhi-yuan¹,
QU Xuan-hui^1,2,3

1) Institute of Advance Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China
2) Beijing Laboratory of Metallic Materials and Processing for Modern Transportation, Beijing 100083, China
3) Beijing Key Laboratory for Advanced Powder Metallurgy and Particulate Materials, Beijing 100083, China

摘要

摘要: 以純Al粉為主要原料,添加Cu單質粉末以及Al-Mg、Al-Si中間合金粉,利用粉末冶金壓制燒結方法制備出相對密度98%以上的Al-Mg-Si-Cu系鋁合金.研究表明,燒結致密化過程主要分為3個階段:初始階段(室溫~460℃),坯體內首先形成Al-Mg合金液相,液相中的Mg原子分別擴散至Al或Al-Si粉末中,與Al₂O₃反應并破除氧化膜,形成Al-Mg-O等化合物;同時,Al-Cu發生互擴散,形成Al₂Cu等金屬間化合物.第二階段(460~560℃),Al-Cu、Al-Si液相快速填充顆粒縫隙或孔洞,坯體相對密度顯著提高;此階段的致密化機制主要是毛細管力引起的顆粒重排,以及溶解析出導致的晶界平直化.第三階段(560~600℃),隨溫度的升高,液相潤濕性提高,晶粒快速長大,使得大尺寸孔洞填充,燒結體基本實現全致密,此階段的致密化主要由填隙機制控制.在鋁合金晶界處發現了MgAl₂O₄和MgAlCuO氧化物的存在,推測Al粉表面氧化膜的破除機制與合金成分有關.由于Al-Cu液相在Al表面的潤濕速率遠高于AlN的生長速率,因為在本體系中未發現AlN的存在.
- 粉末冶金 /
- 固相擴散 /
- 液相燒結 /
- 氧化膜 /
- 氮化鋁
Abstract: In this study, an Al-Mg-Si-Cu alloy was prepared by conventional press-and-sinter powder metallurgy techniques using pure Al powder, Cu element powder, and binary Al-Mg and Al-Si powders to investigate the processes of atom diffusion and microstructure evolution. The relative density of the sintering samples exceeded 98%. It is found that the sintering densification process can be approximately divided into three stages. In the first stage (from room temperature to 460℃), after the Al-Mg eutectic liquid phase formed at 450℃, the Mg atoms in the liquid diffuses into Al and Al-Si particles and reacts with Al₂O₃ at the metal/oxide interface to form an Al-Mg-O compound. Meanwhile, the interdiffusion between Al and Cu leads to the formation of Al₂Cu compounds. In the second stage (from 460 to 560℃), the micro-channels or small holes between the grain boundaries are rapidly filled by Al-Cu and Al-Si eutectic liquids, which leads to a significant increase of density. In this stage, the densification mechanisms are particle rearrangement controlled by the capillary driving force and contact flattening dominated by solution-reprecipitation. In the last stage (from 560 to 600℃), the residual large holes are finally filled by the liquid because of the enhancement of wettability and grain growth with the increase of sintering temperature. In this stage, the densification mechanism is mainly pore-filling, resulting from the grain growth. The sample is fully dense through this stage. In addition, MgAl₂O₄ and MgAlCuO compounds are found in the grain boundary region; thus, it can be speculated that the mechanism of oxide film disruption is related to the alloy composition. Furthermore, because of the good wettability between Al-Cu liquid and Al, the surface of Al particles is quickly wetted by the liquid under the capillary driving force; therefore, no AlN is found in the grain boundary region in this research.
- powder metallurgy /
- solid diffusion /
- liquid-phase sintering /
- oxide film /
- aluminum nitride

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