Mechanical behavior of additively manufactured GRCop-84 copper alloy lattice structures
Mechanical behavior of additively manufactured GRCop-84 copper alloy lattice structures
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DOI：
10.1016/j.addma.2022.102928
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发表时间：
2022-06-04
影响因子：
11
通讯作者：
Babamiri, Behzad Bahrami
中科院分区：
文献类型：
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作者：
Hazeli, Kavan;June, Daniel;Babamiri, Behzad Bahrami
研究了添加法制备铜铬铌合金(GRCop-84)晶格结构的微观结构、拓扑结构及其联合作用对准静态和动态行为的影响。由GRCop-84合金制成的晶格结构由于结合了GRCop-84赋予的高强度和导热性，同时通过使用晶格结构最大限度地减少重量和增加能量吸收，因此有利于广泛的应用。用X射线计算机断层扫描(XCT)和光学显微镜分别表征了气孔率和晶粒结构。在10(-1)S(-1)和10(3)S(-1)应变速率下对AB试件进行了准静态和动态试验。观察表明，将单位晶胞尺寸从4 mm减小到2 mm时，孔隙率降低了66%。根据测试样品的拓扑结构，2 mm单位单元样品中孔隙率的减少导致压缩屈服强度增加35%至60%。为了了解拓扑是否是影响力学性能(如屈服强度)的唯一驱动机制，在保持拓扑不变的情况下，通过热等静压(HIP)热处理改变了组织。注意到，4 mm的单元尺寸对HIPing的响应更好，孔隙率减少了40%，而2 mm的单元尺寸仅经历了28%的孔隙率减少。还注意到，在HIPed样品的情况下，通过将单位晶胞尺寸从4 mm减小到2 mm，孔隙率降低了48%。利用这些数据，认识到微观结构和拓扑结构之间的相关性。研究发现，与AB相比，HIPed样品经历了更多的塑性变形，并表现出多孔固体中常见的应力平台，表明其能量吸收能力有所提高。AB样品表现出较高的抗压强度，由于AB微观结构的脆性而失效。晶胞尺寸为4 mm和2 mm的晶格结构经历了不同的崩塌机制，其中2 mm晶格与拓扑有关，4 mm晶格与微结构有关。
This study investigates the interplay between microstructure, topology and their combined effect on the quasi static and dynamic behavior of additively manufactured Copper-Chromium-Niobium alloy (GRCop-84) lattice structures. Lattice structures made of GRCop-84 alloys are beneficial for wide range of applications due to the combination of the high strength and thermal conductivity imparted by GRCop-84 while minimizing weight and increasing the energy absorption through the use of the lattice structure. X-ray computed tomography (XCT) and optical microscopy were used to characterize the porosity and grain structure, respectively. Quasi static and dynamic testing was performed on the as-built (AB) samples at strain rates of 10(-1)s(-1) and 10(3)s(-1), respectively. The observations indicated that reducing the unit cell size from 4 mm to 2 mm led to a 66% reduction in porosity. Depending on the topology of the tested sample, the reduced porosity within the 2 mm unit cell samples resulted in a 35% to 60% increase in the compressive yield strength. To understand whether topology is the only driving mechanism that influence the mechanical properties e.g., yield strength, the microstructure was altered through hot isostatic pressing (HIP) heat treatment while the topology was kept constant. It was noted that the 4 mm unit cell size was more responsive to HIPing with a 40% reduction in porosity, while the 2 mm unit cell size only experienced a 28% reduction in porosity. It was also noticed that there was a 48% reduction in porosity by minimizing the unit cell size from 4 mm to 2 mm in the case of the HIPed samples. Using this data, a correlation was recognized between microstructure and topology. It was found that HIPed samples experienced more plastic deformation and exhibited stress plateau that is common in cellular solids, indicating improved energy absorbing abilities compared to AB. AB Samples demonstrated higher compressive strength and failed due to the brittle nature of the AB microstructure. Lattice Structures with unit cell sizes of 4 mm and 2 mm experienced different collapse mechanisms, with 2 mm unit cell lattices being topology dependent and 4 mm unit cell lattices dependent on microstructure.