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Obtaining heterogeneous α laths in selective laser melted Ti–5Al–5Mo–5V–1Cr–1Fe alloy with high strength and ductility
Materials Science and Engineering: A ( IF 6.4 ) Pub Date : 2022-01-07 , DOI: 10.1016/j.msea.2022.142624
Taomei Zhang 1 , Hualong Huang 1 , Seyed Reza Elmi Hosseini 2 , Wei Chen 3 , Feng Li 1 , Chao Chen 1 , Kechao Zhou 1
Affiliation  

In this study, direct ageing treatments have been employed to improve the strength of selective laser melted near β titanium alloy Ti–5Al–5Mo–5V–1Cr–1Fe (Ti-55511). The microstructure evolution and mechanical behavior of Ti-55511 alloy were systematically investigated. It was demonstrated that the high-density α laths were precipitated with the martensite and the dislocations in as-deposited Ti-55511 as nucleation sites. The alloy aged at or below 600 °C showed the ultimate tensile strength (UTS) as high as 1500 MPa, while the ductility is poor owing to the precipitation of needle-like α laths or isothermal ω phase. With the increase of ageing temperature, the tip curvature of α laths decreased, and all the α laths coarsened, as well as α phase precipitate-free zones (PFZ) are more pronounced, which leads to insufficient strength and ductility of aged Ti-55511. This, therefore, suggests a new duplex ageing treatment to regulating the microstructure and mechanical properties of Ti-55511 alloy. The alloy obtained heterogeneous α laths consist of micron-sized primary α laths and nano-sized secondary α laths, which retain a maximum elongation of 10% with the high UTS of 1264 MPa. The nano-sized secondary α laths are randomly distributed in the β grain and the width of PFZ decreases, which is helpful to improve the ductility of the alloy. In addition, the high density of twinning deformations was observed in the duplex aged Ti-55511, indicating an excellent ability to accommodate the deformation straining under high stress.



中文翻译:

在选择性激光熔化的高强度和延展性 Ti-5Al-5Mo-5V-1Cr-1Fe 合金中获得异质 α 板条

在这项研究中,采用直接时效处理来提高选择性激光熔化的近 β 钛合金 Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) 的强度。系统研究了Ti-55511合金的显微组织演变和力学行为。结果表明,高密度 α 板条以马氏体和沉积态 Ti-55511 中的位错为形核位置析出。合金在600 ℃或以下时效时的极限抗拉强度(UTS)高达1500 MPa,而由于针状α板条或等温ω相的析出,延展性较差。随着时效温度的升高,α板条的尖端曲率减小,α板条全部粗化,α相无析出区(PFZ)更加明显,这导致时效Ti-55511的强度和延展性不足。因此,这提出了一种新的双相时效处理来调节 Ti-55511 合金的微观结构和机械性能。合金获得的异质α板条由微米尺寸的初级α板条和纳米尺寸的次级α板条组成,它们保持10%的最大伸长率和1264 MPa的高UTS。纳米级次生α板条随机分布在β晶粒中,PFZ宽度减小,有利于提高合金的延展性。此外,在双相时效 Ti-55511 中观察到高密度的孪晶变形,表明其具有出色的适应高应力下变形应变的能力。提出了一种新的双相时效处理来调节 Ti-55511 合金的微观结构和机械性能。合金获得的异质α板条由微米尺寸的初级α板条和纳米尺寸的次级α板条组成,它们保持10%的最大伸长率和1264 MPa的高UTS。纳米级次生α板条随机分布在β晶粒中,PFZ宽度减小,有利于提高合金的延展性。此外,在双相时效 Ti-55511 中观察到高密度的孪晶变形,表明其具有出色的适应高应力下变形应变的能力。提出了一种新的双相时效处理来调节 Ti-55511 合金的微观结构和机械性能。合金获得的异质α板条由微米尺寸的初级α板条和纳米尺寸的次级α板条组成,它们保持10%的最大伸长率和1264 MPa的高UTS。纳米级次生α板条随机分布在β晶粒中,PFZ宽度减小,有利于提高合金的延展性。此外,在双相时效 Ti-55511 中观察到高密度的孪晶变形,表明其具有出色的适应高应力下变形应变的能力。在 1264 MPa 的高 UTS 下保持 10% 的最大伸长率。纳米级次生α板条随机分布在β晶粒中,PFZ宽度减小,有利于提高合金的延展性。此外,在双相时效 Ti-55511 中观察到高密度的孪晶变形,表明其具有出色的适应高应力下变形应变的能力。在 1264 MPa 的高 UTS 下保持 10% 的最大伸长率。纳米级次生α板条随机分布在β晶粒中,PFZ宽度减小,有利于提高合金的延展性。此外,在双相时效 Ti-55511 中观察到高密度的孪晶变形,表明其具有出色的适应高应力下变形应变的能力。

更新日期:2022-01-12
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