初晶Si与Mg_2Si颗粒互补增强Al基梯度复合材料的离心成形机制（英文）  

Centrifugal Forming Mechanism of Al Gradient Composites Reinforced with Complementary Primary Si and Mg_2Si Particles

作　　者：翟彦博[1] 马秀腾[1] 梅镇 

机构地区：[1]西南大学,重庆400715 [2]重庆机床(集团)有限责任公司,重庆400055

出　　处：《稀有金属材料与工程》2014年第4期769-774,共6页Rare Metal Materials and Engineering

基　　金：National Natural Science Foundation of China(51201140);The Fundamental Research Funds for the Central Universities(XDJK2010C007)

摘　　要：为了克服单一初晶Si或Mg2Si颗粒增强的铝基复合材料的不足,采用离心铸造的方法制备了一种由初晶Si与Mg2Si两种颗粒互补增强的铝基梯度复合材料。这种复合材料的组织与性能具有明显的梯度分布特征:内层含有高体积分数的初晶Si与Mg2Si颗粒,形成互补增强区域,具有高硬度的特点;外层没有或含有极少量初晶颗粒,形成非增强区域,具有硬度低的特点。对该复合材料的离心成形机制探讨发现,大量细小的初晶Mg2Si颗粒是形成这种梯度复合材料的关键因素。在离心力场中,密度更小的初晶Mg2Si颗粒具有比初晶Si颗粒大得多的向心运动速度,在运动过程中它与初晶Si发生碰撞并推动后者一起快速运动,最终导致二者在内层的剧烈偏聚。此外,为了获得足够的初晶Mg2Si颗粒,在三元Al-Si-Mg合金中,Si的质量分数应不低于19%,Mg的质量分数应不低于4%。To overcome the shortages of Al composites reinforced with a single primary Si or Mg2Si particles, a new type of gradient composites reinforced with the two particles was investigated through centrifugal casting. The structures and the properties of the composites have the obvious gradient distribution characteristics. The inner zone is the reinforced zone with a high volume fraction of primary Si and MgESi particles, whereas the external zone is the unreinforced zone with few or no primary Si and MgESi particles. Due to the high volume fraction of the complementary particles, the hardness values of the inner zone are much more than that of the external zone. The assembling mechanism analysis reveals that the massive primary Mg2Si particles are the key factor to form the gradient composites. In the centrifugal field, the relative velocity of the lower density primary Mg2Si particles is higher than that of primary Si particles. The MgESi particles will collide and impel primary Si particles to move more quickly towards the inner zone of tubular parts during freezing, resulting in a strong concentration of the primary Si and MgESi particles in the inner zone. To obtain the enough primary Mg2Si particles, the amount of Si should not be lower than 19 wt% and that of Mg not lower than 4 wt% in ternary AI-Si-Mg alloys.

关 键 词：梯度复合材料 颗粒增强复合材料 初晶SI 初晶Mg2Si 离心铸造 

分 类 号：TB333[一般工业技术—材料科学与工程]