Raji Sadiq Abiola, Popoola Abimbola Patricia Idowu
Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, P.M.B. X680, Pretoria, South Africa.
Heliyon. 2024 Feb 2;10(4):e25519. doi: 10.1016/j.heliyon.2024.e25519. eCollection 2024 Feb 29.
So as to explore the opportunity of property enhancement of TiAl-based alloys, studies of microstructural evolution after processing with heat treatments are to be expected. Therefore, the objective of this present study is to investigate how additions of silicon (Si) and molybdenum (Mo) as alloying elements affects the microstructure, microhardness, corrosion behaviour, and wear properties of Ti-Al-x(Mo, Si) alloys made from constituent elemental powders through in-situ alloying laser engineered net shaping (LENS) technique. The influence of the feed rate of Si powder (0.1 rpm, 0.2 rpm and 0.3 rpm) on Ti-Al-xMo was studied at 0.1 rpm and 0.2 rpm Mo feed rate, respectively. Heat treatment at 1200 °C for 15, 30, and 60 min was performed after LENS in-situ alloying, and furnace cooling (FC) was the final step. The microstructure of the produced alloys was analyzed via Scanning electron microscopy (SEM) fitted with energy dispersive spectroscopy (EDS). Using a tribometer and a potentiodynamic polarization test, the alloys' wear characteristics and corrosion behaviour were studied. Based on the results, it was noticed that microhardness values decrease after heat treatment for all the samples produced. Owing to the combined effects of Mo and Si, both the β-TiAl and -TiSi phases lead to solid precipitation hardening and solution strengthening at the grain boundaries. The XRD analysis confirmed γ, α, α, β and ζ-TiSi phases occurrence in the as-built alloys. The LENS fabricated alloys demonstrated improved wear properties and marginally change in corrosion behavior after heat treatment.
为了探索提高TiAl基合金性能的机会，预期将开展关于热处理后微观结构演变的研究。因此，本研究的目的是研究添加硅（Si）和钼（Mo）作为合金元素如何影响通过原位合金化激光工程净成形（LENS）技术由组成元素粉末制成的Ti-Al-x（Mo，Si）合金的微观结构、显微硬度、腐蚀行为和磨损性能。分别在0.1 rpm和0.2 rpm的Mo进料速率下研究了Si粉末进料速率（0.1 rpm、0.2 rpm和0.3 rpm）对Ti-Al-xMo的影响。在LENS原位合金化后，于1200°C进行15、30和60分钟的热处理，最后进行炉冷（FC）。通过配备能谱仪（EDS）的扫描电子显微镜（SEM）分析所制备合金的微观结构。使用摩擦磨损试验机和动电位极化试验研究了合金的磨损特性和腐蚀行为。基于这些结果，注意到所有制备的样品在热处理后显微硬度值均降低。由于Mo和Si的综合作用，β-TiAl和-TiSi相均导致在晶界处发生析出硬化和固溶强化。XRD分析证实了在增材制造合金中存在γ、α、α、β和ζ-TiSi相。LENS制造的合金在热处理后表现出改善的磨损性能，并且腐蚀行为略有变化。
