粘结剂喷射制造高强韧93W-4.9Ni-2.1Fe合金的烧结和热处理工艺研究

Research on the sintering and heat treatment process for fabricating strong and tough 93W-4.9Ni-2.1Fe alloy via binder jetting

摘要:

粘结剂喷射技术理论上兼顾增材制造和粉末冶金法的工艺优点,可实现钨镍铁合金复杂异形部件的高性能、高精度一体成形,但当前适用于制造高强韧钨镍铁合金产品的优选工艺参数仍不明确。本文系统研究了烧结温度、烧结时间及热处理制度等对粘结剂喷射制造93W-4.9Ni-2.1Fe合金物相组成、微观织构和力学性能的影响规律,阐明了真空脱氢和循环淬火两种热处理制度的强韧化机理。结果表明,烧结温度是影响粘结剂喷射制造93W-4.9Ni-2.1Fe合金物理和机械性能的关键因素,其数值设计应超出粉末冶金法至少20 ℃为宜。真空脱氢主要通过改善Ni-Fe相韧性实现对合金的韧化,而循环淬火则通过减少W-W连接度进而缓解W-W界面应力集中获得韧化。两种热处理制度协同使用,样品的抗拉强度和断裂伸长率分别达到938 MPa和18.7%,较未热处理样品相应提高13.4%和253%。

Abstract:

Binder jetting is a technology that combines the advantages of both additive manufacturing and powder metallurgy, which can fabricate complex-shaped W-Ni-Fe alloy components with good mechanical properties and dimensional accuracy. Since the optimal process parameters for manufacturing strong and tough W-Ni-Fe alloy via binder jetting are still not publicly reported, this study systematically investigates the influence of the sintering temperature, sintering time, and heat treatment process on the phase composition, microstructure, and mechanical properties of 93W-4.9Ni-2.1Fe alloy produced by binder jetting. The strengthening and toughening mechanisms of different heat treatment processes (vacuum dehydrogenation and cyclic quenching) were analyzed in detail. The results indicate that the impacts of sintering temperature on the physical and mechanical properties of 93W-4.9Ni-2.1Fe alloy are much greater than sintering time, and its numerical design should exceed the powder metallurgy method by at least 20 ℃. In terms of the strengthening and toughening mechanism, vacuum dehydrogenation mainly improves toughness by toughening the Ni-Fe phase, while cyclic quenching mainly improves toughness by reducing the connectivity between W particles and then changing the fracture behavior of W phases. The synergistic use of vacuum dehydrogenation and cyclic quenching resulted in tensile strength and elongation at break of the samples reaching 938 MPa and 18.7%, respectively, which were 13.4% and 253% higher than those of the untreated samples.