Ni基单晶高温合金中合金化元素对裂纹扩展作用的原子学模拟

发布时间：2018-08-03 08:34

【摘要】：镍基单晶高温合金具有优异的高温力学特性,现已被广泛用于航空发动机和燃气涡轮发动机的叶片材料。由于镍基单晶高温合金化学成分和结构特性的原一。因,γ/γ'相界面性质在高温下具显著作用。Y/Y'相界面也是裂纹扩展的主要因素之Ni3Al相是镍基单晶高温合金重要的强化相,对高温合金的力学特性有重要影响。诸如Re、Ru、Mo、W、Ta等合金化元素的掺入,可有效提高镍基高温合金Y/γ'相界面的力学强度,改善高温合金的稳定性。本文基于分子动力学方法以及改进的多组元埋置原子(EAM)势：Ni-Al-X (X= Re、Ru、Co、W),结合第一原理离散变分方法,分析探讨了合金化元素对Ni基单晶高温合金中裂纹扩展的影响。本文研究了不同温度下(5 K和1273 K)下,合金化元素Re、Ru、Co、W分别对Ni/Ni3Al相界面裂纹扩展的影响。结果表明,Re、Ru和W可能提高材料抗形变能力、具有强化材料的作用。低温(5 K)下,Re、Ru、W抑制裂尖原子键断裂和裂纹脆性扩展,其中W的作用最明显；而Co有加重裂纹脆性扩展倾向：高温下,Re、Ru、W增强裂尖钝化程度。低温(5 K)和高温(1273 K)下,W对Ni/Ni3Al相界面裂纹扩展效应最强。我们阐明了低温下合金化元素Re、Ru、W使Ni/Ni3Al相界面裂纹扩展速度降低的原因,以及高温下Re、Ru、Co、W促进裂尖位错发射的机理。本文探索了合金化元素Re和W在三种裂纹取向(101)[010]、(010)[001]和(010)[101]对Ni3Al相裂纹脆性断裂的影响。模拟发现,合金化元素Re和W具有强化Ni3Al合金效应、提高材料抗形变的能力；Re和W可具有抑制裂纹脆性扩展、促进裂纹愈合的能力,且W的效应强于Re。Re和W均可提高Ni3Al中裂纹扩展所需的临界断裂应力,且W效应强于Re。Ni-Re和Ni-W的原子键合强度大于Ni-Al键强,且Ni-W原子间相互作用最强。
[Abstract]:Nickel-based single-crystal superalloys have been widely used as blade materials for aero-engines and gas turbine engines because of their excellent high temperature mechanical properties. Due to the chemical composition and structural properties of nickel-based single-crystal superalloy. Because the interfacial properties of 纬 / 纬 'phase play a significant role at high temperature. The interface of Y / Y' phase is also the main factor of crack growth. The Ni3Al phase is an important strengthening phase of Nickel-based single crystal superalloy, which has an important effect on the mechanical properties of the superalloy. The addition of alloying elements such as Reu Ru-Mo Mo-Ta can effectively improve the mechanical strength of the Y- / 纬 'phase interface of Ni-base superalloy and improve the stability of the superalloy. Based on the molecular dynamics method and the modified multicomponent buried atom (EAM) potential: Ni-Al-X (X = Re-Ru-CoW) and the first principle discrete variation method, the effect of alloying elements on the crack propagation in Ni-based single crystal superalloy has been investigated. The effect of alloying element Reo Ru-CoW on the crack propagation at the interface of Ni/Ni3Al phase at different temperatures (5 K and 1273 K) has been studied in this paper. The results show that Ru and W may improve the deformation resistance of the materials and have the effect of strengthening the materials. At low temperature (5 K), Reruw inhibited crack tip atomic bond fracture and crack brittleness growth, among which W had the most obvious effect, while Co had a tendency to aggravate crack brittle growth: Reruw enhanced crack tip passivation at high temperature. Low temperature (5 K) and high temperature (1273 K) have the strongest effect on the crack growth of Ni/Ni3Al interface. The causes of the decrease of crack growth rate at the interface of Ni/Ni3Al phase due to the alloying element Reo Ru-W at low temperature and the mechanism of promoting dislocation emission from the crack tip at high temperature have been elucidated. In this paper, the effects of alloying elements re and W on the brittle crack fracture of Ni3Al phase in three crack orientations (101) [010], (010) [001] and (010) [101] have been investigated. It is found that the alloying elements re and W can strengthen the effect of Ni3Al alloy, and improve the deformation resistance of the materials. Re and W can inhibit the crack brittle growth and accelerate the crack healing. The effect of W is stronger than that of Re.Re and W in increasing critical fracture stress of crack propagation in Ni3Al, and W effect is stronger than that of Re.Ni-Re and Ni-W, and the bond strength of Re.Ni-Re and Ni-W is stronger than that of Ni-Al, and the interaction between Ni-W atoms is strongest.
【学位授予单位】：钢铁研究总院
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG132.3

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