Relating fracture toughness to micro-pillar compression response for a laser powder bed additive manufactured bulk metallic glass
Relating fracture toughness to micro-pillar compression response for a laser powder bed additive manufactured bulk metallic glass
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DOI：
10.1016/j.msea.2019.138535
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发表时间：
2020-01-07
期刊：
影响因子：
6.4
通讯作者：
Kruzic, Jamie J.
中科院分区：
文献类型：
--
作者：
Best, James P.;Ast, Johannes;Kruzic, Jamie J.
采用选择性激光熔化（SLM）制备的Zr基块体金属玻璃与采用传统吸铸法制备的相同合金进行了比较。通过单边切口梁弯曲实验对断裂韧性的分析表明，激光处理的材料的损伤容限显著降低（K-Q类似于138.0 +/- 13.1 -> 28.7 +/- 3.7 MPa均方根），即使X射线衍射和显微硬度响应是相同的。使用单轴准静态微柱压缩，人们发现，铸态样品更容易进行剪切变形（通过离散的负载下降证明）低于标称0.2%的屈服应力，这是连接到更高的宏观韧性。差示扫描量热法表明，SLM材料的剪切转变势垒的增加不能用相对弛豫状态来解释。相反，这是由于激光处理的材料中的溶解氧浓度更高，这被假定为降低结构中的原子迁移率，从而增加启动剪切转变所需的活化能。
A Zr-based bulk metallic glass produced using selective laser melting (SLM) was compared to the same alloy fabricated using traditional suction-casting. Analysis of the fracture toughness through single edge notched beam bending experiments showed a significantly reduced damage tolerance for the laser-processed material (K-Q similar to 138.0 +/- 13.1 -> 28.7 +/- 3.7 MPa root m), even though X-ray diffraction and microhardness responses were identical. Using uniaxial quasistatic micro-pillar compression, it was found that as-cast samples more readily underwent shear transformations (evidenced through discrete load drops) below the nominal 0.2% yield stress, which was connected to the higher macroscopic toughness. Differential scanning calorimetry demonstrated that the increased barrier to shear transformation for the SLM material could not be explained by the relative relaxation states. Rather, it was attributed to the greater dissolved oxygen concentration in the laser-processed material, which is postulated to decrease atomic mobility in the structure and thereby increase the activation energy required to initiate shear transformations.