發(fā)布時間：2018-04-30 10:27

  本文選題：TiAl合金 + 包套鍛造�。� 參考：《金屬學報》2017年09期

【摘要】：對Ti-43Al-4Nb-1.5Mo合金進行包套鍛造和后續(xù)熱處理實驗,考察了該過程TiAl合金的熱變形行為、流變軟化機制以及熱處理參數(shù)對微觀組織和力學性能的影響。結果表明,TiAl合金包套鍛造過程的高溫流變軟化以β相協(xié)調變形、片層相變分解、g相內位錯滑移以及孿晶誘導的動態(tài)再結晶為主,最終組織為殘余α_2/γ層片和等軸α_2、γ、B2相的混合組織。隨熱處理溫度的升高,熱變形組織由殘余α_2/γ層片和多相混合組織轉變?yōu)棣羅2/γ層片+γ相組織,在較高的溫度下(1300℃)轉變?yōu)槿珜悠M織。其中,B2相隨著溶質擴散程度的增加逐漸消失,殘余層片組織發(fā)生分解轉變?yōu)榈容Sα_2/γ層片團,同時發(fā)生γ→α轉變,形成全層片組織。對熱等靜壓、鍛態(tài)和熱處理試樣的高溫(800℃)拉伸性能進行比較,經熱處理后獲得的全片層組織具有最佳的綜合性能,抗拉強度為663 MPa,延伸率達到26%。分析該樣品的斷裂行為可知,由于存在層片扭曲拉長、微孔鈍化以及裂紋曲折延伸的斷裂機制,全層片組織具有良好強度-塑性的綜合力學性能。另外,熱加工過程中(高溫)bcc結構B2相能夠協(xié)調變形,但服役條件下硬脆的B2相作為裂紋源容易引起裂紋萌生,對力學性能極其不利。因此,TiAl合金在熱變形和服役過程中需要對組成相進行嚴格控制,從而獲得良好的力學性能。
[Abstract]:The hot deformation behavior, the rheological softening mechanism and the effect of heat treatment parameters on the microstructure and mechanical properties of the Ti-43Al-4Nb-1.5Mo alloy were investigated. The results showed that the high temperature flow softening in the forging process of the TiAl alloy was characterized by the coordination deformation of the beta phase, the decomposition of the lamellar phase transformation, and the g of G. The internal dislocation slip and the twin induced dynamic recrystallization are the main structure, and the final microstructure is the mixed structure of the residual alpha _2/ gamma layer and the equiaxed alpha _2, gamma, B2 phase. With the increase of heat treatment temperature, the thermal deformed tissue is transformed from the residual alpha _2/ lamella and polyphase mixture to the alpha _2/ gamma layer + gamma phase tissue, and at a higher temperature (1300 degrees C) to the whole layer. Among them, B2 is gradually disappearing with the increase of the degree of solute diffusion, and the decomposition of the residual layer is transformed into an isoaxial alpha _2/ gamma layer mass, and the whole layer tissue is formed by gamma to alpha transformation. The tensile properties of the hot isostatic pressure, forged and heat treated specimens are compared, and the whole layer tissue obtained after heat treatment is obtained. With the best comprehensive properties, the tensile strength is 663 MPa, and the elongation reaches 26%. analysis of the fracture behavior of the sample. It is known that the whole layer tissue has good strength and plastic comprehensive mechanical properties because of the existence of lamellar distortion lengthening, microvoid passivation and the zigzag extension of the crack. In addition, the B2 phase of the bcc structure during hot processing (high temperature) is in the process of heat processing. It can coordinate deformation, but the hard and brittle B2 phase as a crack source can cause crack initiation easily under service conditions, and it is extremely unfavorable to mechanical properties. Therefore, TiAl alloy needs to strictly control the composition phase in the process of thermal deformation and service, so as to obtain good mechanical properties.

【作者單位】： 東北大學軋制技術與連軋自動化國家重點實驗室;東北大學材料科學與工程學院;
【基金】：國家重點研發(fā)計劃項目Nos.2016YFB0301200和2016YFB0300603 國家自然科學基金項目No.51504060 中央高校基本科研業(yè)務費項目No.N140703003 遼寧省科技項目博士啟動基金項目No.201501150~~
【分類號】：TG146.23;TG166.5;TG316

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本文編號：1824190