發(fā)布時(shí)間：2018-04-30 10:27

  本文選題：TiAl合金 + 包套鍛造�。� 參考：《金屬學(xué)報(bào)》2017年09期

【摘要】：對(duì)Ti-43Al-4Nb-1.5Mo合金進(jìn)行包套鍛造和后續(xù)熱處理實(shí)驗(yàn),考察了該過(guò)程TiAl合金的熱變形行為、流變軟化機(jī)制以及熱處理參數(shù)對(duì)微觀組織和力學(xué)性能的影響。結(jié)果表明,TiAl合金包套鍛造過(guò)程的高溫流變軟化以β相協(xié)調(diào)變形、片層相變分解、g相內(nèi)位錯(cuò)滑移以及孿晶誘導(dǎo)的動(dòng)態(tài)再結(jié)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(zhuǎn)變?yōu)棣羅2/γ層片+γ相組織,在較高的溫度下(1300℃)轉(zhuǎn)變?yōu)槿珜悠M織。其中,B2相隨著溶質(zhì)擴(kuò)散程度的增加逐漸消失,殘余層片組織發(fā)生分解轉(zhuǎn)變?yōu)榈容Sα_2/γ層片團(tuán),同時(shí)發(fā)生γ→α轉(zhuǎn)變,形成全層片組織。對(duì)熱等靜壓、鍛態(tài)和熱處理試樣的高溫(800℃)拉伸性能進(jìn)行比較,經(jīng)熱處理后獲得的全片層組織具有最佳的綜合性能,抗拉強(qiáng)度為663 MPa,延伸率達(dá)到26%。分析該樣品的斷裂行為可知,由于存在層片扭曲拉長(zhǎng)、微孔鈍化以及裂紋曲折延伸的斷裂機(jī)制,全層片組織具有良好強(qiáng)度-塑性的綜合力學(xué)性能。另外,熱加工過(guò)程中(高溫)bcc結(jié)構(gòu)B2相能夠協(xié)調(diào)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(duì)力學(xué)性能極其不利。因此,TiAl合金在熱變形和服役過(guò)程中需要對(duì)組成相進(jìn)行嚴(yán)格控制,從而獲得良好的力學(xué)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(xué)軋制技術(shù)與連軋自動(dòng)化國(guó)家重點(diǎn)實(shí)驗(yàn)室;東北大學(xué)材料科學(xué)與工程學(xué)院;
【基金】：國(guó)家重點(diǎn)研發(fā)計(jì)劃項(xiàng)目Nos.2016YFB0301200和2016YFB0300603 國(guó)家自然科學(xué)基金項(xiàng)目No.51504060 中央高�；究蒲袠I(yè)務(wù)費(fèi)項(xiàng)目No.N140703003 遼寧省科技項(xiàng)目博士啟動(dòng)基金項(xiàng)目No.201501150~~
【分類號(hào)】：TG146.23;TG166.5;TG316

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