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  本文選題：非晶合金復合材料　切入點：加工硬化　出處：《深圳大學》2017年碩士論文

【摘要】：非晶合金是指固態(tài)合金中原子的三維空間結構呈現無序排列的合金。由于非晶合金不存在空位、位錯等結構缺陷,使其具有很多獨特和優(yōu)異的力學、物理和化學性能,例如高強度、高斷裂韌性、高硬度、大彈性極限、低彈性模量等。但非晶合金卻存在一個致命的缺陷-應變軟化,這極大的限制了其作為結構材料的應用。因此非晶合金的復合化是目前解決非晶合金應變軟化的主要突破方向。本論文我們設計并制備了新的Ti_(38.5)Ni_(38.5)Nb_(20.5)Zr_(2.5)和Cu_(47.2)Zr_(47.2)Nb_(5.6)兩種非晶復合材料,使其分別具有NiTi相和CuZr相。并通過控制制備工藝使獲得的樣品具有形變誘導相變的效應即TRIP(Transformation-Induced Plasticity)效應,發(fā)現兩種非晶合金樣品都具有優(yōu)異的室溫塑性變形能力并伴隨明顯的應變硬化現象。全新設計高Nb含量的Ti_(38.5)Ni_(38.5)Nb_(20.5)Zr_(2.5)合金含有約15%(vol)B2相,具有22.1%的工程塑性應變和高達2400MPa的抗壓強度。合金的微觀組織為Ni-Nb-β枝晶、B2-Ni-Ti形狀記憶相和非晶基體。變形時晶態(tài)相內部產生的位錯和嚴重的晶格畸變,導致合金具有應變硬化行為。晶內變形及對多重剪切帶的誘導作用,抑制了單一剪切帶的失穩(wěn)擴展,從而使合金具有大的塑性應變。通過控制樣品尺寸,成功制備了直徑為1.0mm,1.5mm,2.0mm,2.5mm的棒狀Cu_(47.2)Zr_(47.2)Nb_(5.6)非晶復合材料。復合材料由非晶基體和直徑約為200nm的B2-CuZr馬氏體相組成,樣品具有良好的塑性變形能力和優(yōu)異的應變硬化效果。復合材料的塑性變形能力隨B2相的增多呈現先增多后減小的趨勢,當樣品直徑達到1.5mm時樣品含有約15%(vol)B2相,具有最高的抗壓強度和11.3%的最大塑性變形,并伴隨明顯的應變硬化。研究表明,相變吸收彈性應變能,塑性晶體相內部的高密度位錯和攣晶變形,以及非晶/晶相界面的應力集中,是引起非晶復合材料優(yōu)異力學變形行為的本質原因。本研究通過合金成分設計成功制備出兩個全新的非晶復合材料成分,通過第二相的增韌獲得了大的塑性變形能力及明顯的加工硬化,仍保持非晶基體的高強度。這為非晶合金的增韌和進一步工程化應用奠定了基礎。
[Abstract]:Amorphous alloy is a kind of alloy in which the three-dimensional space structure of atoms in solid alloy is disordered. The amorphous alloy has many unique and excellent mechanical, physical and chemical properties due to the absence of vacancies, dislocations and other structural defects. For example, high strength, high fracture toughness, high hardness, large elastic limit, low modulus of elasticity, etc. Therefore, the composite of amorphous alloys is the main breakthrough direction to solve strain softening of amorphous alloys. In this paper, we have designed and prepared two kinds of new amorphous composites, Ti-Li (38.5) Nb-SJ (20.5) and Cu-Li (47.2Zr-47.2N) (5.6). By controlling the preparation process, the obtained samples have the effect of deformation-induced phase transition, that is, the effect of TRIP(Transformation-Induced plasticity. It is found that both amorphous alloy samples have excellent plastic deformation at room temperature and are accompanied by obvious strain hardening. The microstructure of the alloy is Ni-Nb- 尾 dendrite B2-Ni-Ti shape memory phase and amorphous matrix. The strain hardening behavior of the alloy is caused by the deformation within the grain and the induction of the multiple shear band, which inhibits the instability propagation of the single shear band and makes the alloy have a large plastic strain. By controlling the size of the sample, A rod-like Cutix (1.0mm / 1.5mm / 2.0mm / 2.5mm) rod-like composite material was successfully prepared. The composite consists of amorphous matrix and B2-CuZr martensite phase with diameter of about 200nm, and the amorphous composite is composed of amorphous matrix and B2-CuZr martensite with diameter of about 200nm. With the increase of B2 phase, the plastic deformation ability of the composites increased first and then decreased. When the sample diameter reached 1.5mm, the sample contained about 15%(vol)B2 phase. It has the highest compressive strength and 11.3% maximum plastic deformation, accompanied by obvious strain hardening. The results show that the phase transformation absorbs elastic strain energy, high density dislocation and clonic deformation in the plastic crystal phase. The stress concentration at the interface of amorphous / crystalline phase is the essential reason for the excellent mechanical deformation behavior of amorphous composites. In this study, two new amorphous composites were successfully fabricated by alloy composition design. Through the toughening of the second phase, the large plastic deformation ability and the obvious work hardening are obtained, and the high strength of the amorphous matrix is maintained, which lays a foundation for the toughening and further engineering application of the amorphous alloy.
【學位授予單位】：深圳大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG139.8

【參考文獻】

相關期刊論文 前1條

1 ;Development of NiTiNb in-situ composite with high damping capacity and high yield strength[J];Progress in Natural Science:Materials International;2011年04期

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本文編號：1692814