【摘要】：研究了名義成分為Ti-22Al-15Nb的Ti-Al系合金的微觀組織和力學(xué)性能,以及在準(zhǔn)靜態(tài)和動(dòng)態(tài)加載條件下的變形行為,并對其破壞機(jī)理進(jìn)行了分析。微觀組織研究表明,Ti-22Al-15Nb合金鑄態(tài)組織為等軸晶,晶內(nèi)主要由α2-Ti3Al相和B2-Ti2AlNb相組成,具有隨機(jī)取向的片狀α2相均勻分布在B2基相上。力學(xué)性能研究表明,合金在動(dòng)態(tài)加載條件下表現(xiàn)出較優(yōu)異的性能,其屈服強(qiáng)度為1 100 MPa,抗壓強(qiáng)度為1 750 MPa,且在動(dòng)態(tài)加載下具有更好的塑性。破壞機(jī)理分析表明,在準(zhǔn)靜態(tài)加載條件下,合金試樣發(fā)生剪切破壞,微裂紋首先在α2相及α2相與B2相的相界處萌生,在最大剪應(yīng)力方向上擴(kuò)展形成主裂紋,最終導(dǎo)致合金試樣破壞;在動(dòng)態(tài)加載條件下,合金的破壞方式為絕熱剪切破壞,即在與加載軸呈45°角的方向上形成絕熱剪切帶,隨著應(yīng)變的增大,裂紋在剪切帶中萌生并擴(kuò)展,最終破壞合金試樣。
[Abstract]:The microstructure and mechanical properties of Ti-Al alloy with nominal composition of Ti-22Al-15Nb and its deformation behavior under quasi-static and dynamic loading were studied. The failure mechanism of the alloy was analyzed. Microstructure study shows that the as-cast structure of Ti-22Al-15Nb alloy is equiaxed, which is mainly composed of 偽 2-Ti3Al phase and B2-Ti2AlNb phase. The lamellar 偽 2 phase with random orientation distributes uniformly on B2 base phase. The mechanical properties show that the alloy exhibits excellent properties under dynamic loading, its yield strength is 1 100 MPa, compressive strength is 1 750 MPa, and it has better plasticity under dynamic loading. The failure mechanism analysis shows that under the quasi-static loading condition, the shear failure of the alloy specimen occurs, and the microcracks first germinate at the phase boundaries of 偽 2 phase and 偽 2 phase and B2 phase, and form the main crack in the direction of the maximum shear stress. Under dynamic loading condition, the failure mode of the alloy is adiabatic shear failure, that is, the adiabatic shear band is formed in the direction of 45 擄angle to the loading axis. With the increase of strain, the crack begins and expands in the shear band. The final failure of the alloy specimen.
【作者單位】： 北京理工大學(xué)材料學(xué)院;北京航空材料研究院;北京理工大學(xué)爆炸科學(xué)與技術(shù)重點(diǎn)實(shí)驗(yàn)室;
【基金】：國家自然科學(xué)基金(51571033)
【分類號】：TG146.23

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