Toughening of aluminum matrix nanocomposites via spatial arrays of boron carbide spherical nanoparticles
Toughening of aluminum matrix nanocomposites via spatial arrays of boron carbide spherical nanoparticles
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DOI：
10.1016/j.actamat.2015.09.057
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发表时间：
2016-01-15
期刊：
影响因子：
9.4
通讯作者：
Schoenung, Julie M.
中科院分区：
文献类型：
--
作者：
Jiang, Lin;Yang, Hanry;Schoenung, Julie M.
为了提高金属基纳米复合材料的韧性，我们展示了一种策略，涉及到引入纳米粒子的空间阵列。具体而言，我们描述了一种方法来合成的微观结构，其特征在于由阵列的纤维状纳米颗粒丰富（NPR）的区域，包含球形纳米颗粒的碳化硼（Sn-B4 C）嵌入在超细晶（UFG）铝合金基体。采用低温球磨和热挤压相结合的方法获得了这种特殊的组织，并对其力学行为和强化变形机理进行了详细的研究。当与等同的未增强材料相比时，NPR区域阵列的存在有助于拉伸强度增加26%。此外，当与含有均匀分布的纳米颗粒的纳米复合材料相比时，观察到韧性增加30%。NPR区获得的高纳米硬度值和断裂表面上的“拔出”现象的观察表明，NPR区表现为“硬”纤维状单元，可以有效地承受拉伸载荷，从而提高Sn-B4 C的强化效率。此外，由无纳米颗粒（NPF）区域包围的NPR区域阵列的存在导致强度的增强，而延展性的损失有限。这种行为是合理的基础上，一个较低的值的施密德因子在邻近地区的NPR区，再加上在NPF区的位错运动的便利。最后，塑性区的大小的比例的“硬”NPR区的大小被提出作为一个重要的因素，支配的纳米复合材料的整体韧性。(c)2015 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
To enhance the toughness of metal matrix nanocomposites, we demonstrate a strategy that involves the introduction of spatial arrays of nanoparticles. Specifically, we describe an approach to synthesize a microstructure characterized by arrays of fiber-like nanoparticle-rich (NPR) zones that contain spherical nanoparticles of boron carbide (sn-B4C) embedded in an ultrafine grained (UFG) aluminum alloy matrix. A combination of cryomilling and hot-extrusion was used to obtain this particular microstructure, and the mechanical behavior and operative strengthening and deformation mechanisms were investigated in detail. When compared to an equivalent unreinforced material, the presence of the array of NPR zones contributed to a 26% increase in tensile strength. Moreover, when compared to a nanocomposite containing a homogeneous distribution of nanoparticles, a 30% increase in toughness was observed. High nanohardness values obtained for the NPR zones and the observation of "pull-out" phenomena on fracture surfaces, suggest that the NPR zones behave as "hard" fiber-like units that can effectively sustain tensile loading and thereby enhance the strengthening efficiency of sn-B4C. Also, the presence of the array of NPR zones surrounded by nanoparticle-free (NPF) zones led to an enhancement in strength with limited loss in ductility. This behavior was rationalized on the basis of a low value of the Schmid factor in regions adjacent to NPR zones, coupled with the ease of dislocation movement in NPF zones. Finally, the ratio of the plastic zone size to the size of the "hard" NPR zones is proposed as an important factor that governs the overall toughness of the nanocomposite. (c) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.