Dujana Wasif Abu, Ahmad Sazzad, Noman Md Nazmul Haque, Kabir Mohammad Humaun
Department of Materials and Metallurgical Engineering, Chittagong University of Engineering & Technology, Chattogram, 4349, Bangladesh.
Department of Materials Science and Engineering, Khulna University of Engineering & Technology, Khulna, 9201, Bangladesh.
Heliyon. 2024 Sep 24;10(19):e38350. doi: 10.1016/j.heliyon.2024.e38350. eCollection 2024 Oct 15.
The recent trend of high-entropy alloys (HEAs) was studied extensively for their promising mechanical properties, but individual constituents' effects have remained unexplored. In this work, the effects of changing the percentage of elements of HfNbTaTiZr-HEA on the mechanical properties were analyzed during uniaxial tension using molecular dynamics simulation. The tensile strength and modulus of elastic properties of the samples were analyzed. It was found that adding Nb or Ta up to 10 % ( Nb10/Ta10) in the high entropy alloys increased the ultimate tensile strength (UTS) from 2.9 GPa in the base alloy to 3.8/3.9 GPa (Nb10/Ta10) respectively, but further increment of these elements to 30 % resulted in a downgrade of UTS to 2.7 GPa. Similarly, the modulus of elasticity increased from 117.7 (±3) GPa in the base alloy to 137.7/129 (±3) GPa (Nb10/Ta10) respectively, but fell to 112-115 GPa upon further increment. The initial increase in strength could be due to the solid solution strengthening mechanism. However, further increases in these elements might hinder the development of a homogeneous solid solution because of differences in atomic size and crystal structure, which could ultimately reduce the alloy's strength. However, the effect of Ti and Zr follows an opposite trend as compared to Nb and Ta. Furthermore, the optimum composition of HEAs alloys was analyzed using a surface-contour plot and suggests minimizing the inclusion of Ta for maximizing the UTS, E, and %Elongation. Also, the high-temperature behavior of the optimized HEA's alloy was analyzed which showed a deterioration in properties at elevated temperature. The fracture evolution of the samples showed cup and cone-type fractures propagating under strain, the linear thermal expansion coefficient of HfNbTaTiZr-HEA was also calculated and found closer to the literature value.
高熵合金（HEAs）因其具有良好的机械性能而受到广泛研究，但其单个成分的影响仍未得到探索。在这项工作中，使用分子动力学模拟分析了在单轴拉伸过程中改变HfNbTaTiZr-HEA元素百分比对机械性能的影响。分析了样品的拉伸强度和弹性模量。结果发现，在高熵合金中添加高达10%的Nb或Ta（Nb10/Ta10）可使极限抗拉强度（UTS）从基础合金中的2.9 GPa分别提高到3.8/3.9 GPa（Nb10/Ta10），但这些元素进一步增加到30%会导致UTS降至2.7 GPa。同样，弹性模量从基础合金中的117.7（±3）GPa分别增加到137.7/129（±3）GPa（Nb10/Ta10），但进一步增加后降至112 - 115 GPa。强度的最初增加可能归因于固溶强化机制。然而，这些元素的进一步增加可能会由于原子尺寸和晶体结构的差异而阻碍均匀固溶体的形成，这最终可能会降低合金的强度。然而，与Nb和Ta相比，Ti和Zr的影响呈现相反的趋势。此外，使用表面等高线图分析了高熵合金的最佳成分，并建议尽量减少Ta的含量以最大化UTS、E和伸长率。还分析了优化后的高熵合金在高温下的行为，结果表明在高温下性能会恶化。样品的断裂演变显示在应变下杯锥型断裂扩展，还计算了HfNbTaTiZr-HEA的线性热膨胀系数，发现其与文献值接近。
