Cojocaru Vasile Dănuț, Dan Alexandru, Șerban Nicolae, Cojocaru Elisabeta Mirela, Zărnescu-Ivan Nicoleta, Gălbinașu Bogdan Mihai
Faculty of Materials Science and Engineering, National University of Science and Technology Politehnica of Bucharest, 060042 Bucharest, Romania.
Dental Medicine Faculty, University of Medicine and Pharmacy "Carol Davila" Bucharest, 020021 Bucharest, Romania.
Materials (Basel). 2024 May 14;17(10):2312. doi: 10.3390/ma17102312.
The primary focus of the current paper centers on the microstructures and mechanical properties exhibited by a Ti-30Nb-12Zr-5Ta-2Sn-1.25Fe (wt. %) (TNZTSF) alloy that has been produced through an intricate synthesis process comprising cold-crucible induction in levitation, carried out in an atmosphere controlled by argon, and cold-rolling deformation (CR), applying systematic adjustments in the total deformation degree (total applied thickness reduction), spanning from 10% to 60%. The microstructural characteristics of the processed specimens were investigated by SEM and XRD techniques, and the mechanical properties by tensile and microhardness testing. The collected data indicate that the TNZTSF alloy's microstructure, in the as-received condition, consists of a β-Ti phase, which shows polyhedral equiaxed grains with an average grain size close to 82.5 µm. During the cold-deformation processing, the microstructure accommodates the increased applied deformation degree by increasing crystal defects such as sub-grain boundaries, dislocation cells, dislocation lines, and other crystal defects, powerfully affecting the morphological characteristics. The as-received TNZTSF alloy showed both high strength (i.e., ultimate tensile strength close to σ = 705.6 MPa) and high ductility (i.e., elongation to fracture close to ε = 11.1%) properties, and the computed β-Ti phase had the lattice parameter a = 3.304(7) Å and the average lattice microstrain ε = 0.101(3)%, which are drastically influenced by the applied cold deformation, increasing the strength properties and decreasing the ductility properties due to the increased crystal defects density. Applying a deformation degree close to 60% leads to an ultimate tensile strength close to σ = 1192.1 MPa, an elongation to fracture close to ε = 7.9%, and an elastic modulus close to 54.9 GPa, while the computed β-Ti phase lattice parameter becomes a = 3.302(1) Å.
本文的主要关注点是一种Ti-30Nb-12Zr-5Ta-2Sn-1.25Fe（重量百分比）（TNZTSF）合金所呈现的微观结构和力学性能。该合金是通过复杂的合成工艺制备而成，包括在氩气控制的气氛中进行冷坩埚悬浮感应熔炼，以及冷轧变形（CR），并对总变形程度（总施加厚度减少量）进行系统调整，范围从10%到60%。通过扫描电子显微镜（SEM）和X射线衍射（XRD）技术研究了加工试样的微观结构特征，并通过拉伸和显微硬度测试研究了力学性能。收集的数据表明，TNZTSF合金在初始状态下的微观结构由β-Ti相组成，呈现出多面体等轴晶粒，平均晶粒尺寸接近82.5μm。在冷变形加工过程中，微观结构通过增加诸如亚晶界、位错胞、位错线等晶体缺陷来适应增加的施加变形程度，这对形态特征产生了强烈影响。初始状态的TNZTSF合金同时具有高强度（即极限抗拉强度接近σ = 705.6 MPa）和高延展性（即断裂伸长率接近ε = 11.1%）的性能，计算得到的β-Ti相晶格参数a = 3.304(7) Å，平均晶格微应变ε = 0.101(3)%，施加的冷变形对其有显著影响，由于晶体缺陷密度增加，强度性能提高而延展性性能降低。施加接近60%的变形程度会导致极限抗拉强度接近σ = 1192.1 MPa，断裂伸长率接近ε = 7.9%，弹性模量接近54.9 GPa，而计算得到的β-Ti相晶格参数变为a = 3.302(1) Å。
