Zr基塊體非晶合金剪切帶的自修復(fù)及其對合金熱學(xué)性能的影響
發(fā)布時間：2018-09-05 14:41
【摘要】：由于特殊的原子空間排列,非晶合金具有許多優(yōu)于金屬晶體材料的物理、化學(xué)性能,使其在體育用品、航空航天、生物應(yīng)用等很多方面具有極大的應(yīng)用前景。但是,在室溫條件下,非晶合金通過剪切帶來獲得有限的塑性,這使得其在實際生產(chǎn)應(yīng)用過程中受到限制。通過非晶合金剪切帶的自修復(fù)可以延緩剪切帶擴展,因此,研究非晶合金剪切帶的自修復(fù)行為具有重要的理論和實際應(yīng)用意義。本文以Zr_(65)Cu_(15)Ni_(12.5)Al_(7.5)塊體非晶合金作為研究對象,通過在其過冷液相區(qū)間進行熱處理研究了剪切帶的自修復(fù)情況;并采用熱分析法進一步研究了剪切帶自修復(fù)對非晶合金熱學(xué)性能的影響。實驗使用的樣品為:鑄態(tài)試樣(制備好的試樣未做任何處理)、修復(fù)前試樣(鑄態(tài)試樣產(chǎn)生了2%的壓縮塑性變形)、修復(fù)試樣(對修復(fù)前試樣進行了自修復(fù))。研究了在不同的熱處理條件下試樣表面剪切帶的自修復(fù)情況。結(jié)果表明:在633K、643 K和653 K三個不同處理溫度下分別修復(fù)10 min、20 min和30 min后,試樣表面的剪切帶都得到了不同程度的修復(fù)。在修復(fù)溫度相同時,隨著修復(fù)時間的延長,剪切帶修復(fù)程度越明顯;在修復(fù)時間相同的情況下,隨著修復(fù)溫度的升高,剪切帶修復(fù)的程度也越好。XRD測試表明633 K和643 K修復(fù)10 min后的試樣仍為完全的非晶結(jié)構(gòu),而其他修復(fù)條件下的試樣均出現(xiàn)了晶化。采用DSC研究了剪切帶修復(fù)前后試樣熱學(xué)性能的變化。DSC測試結(jié)果表明:在連續(xù)升溫過程中,650 K下修復(fù)10 min后試樣的T_g變化不明顯,T_x、T_p和ΔT_x明顯低于修復(fù)前試樣的。通過Kissinger方法計算得到的鑄態(tài)試樣、修復(fù)前試樣和修復(fù)試樣的玻璃轉(zhuǎn)變激活能分別為252 kJ/mol、263 kJ/mol和270 kJ/mol,晶化激活能分別為238 kJ/mol、255 kJ/mol和296 kJ/mol。在等溫晶化過程中,修復(fù)后試樣的孕育時間明顯縮短。通過Johnson-Mehl-Avrami(JMA)方法計算得到的鑄態(tài)試樣、修復(fù)前試樣和修復(fù)試樣的Avrami指數(shù)n值的范圍分別是1.698~1.991、2.273~2.446和2.15~2.30,表明其等溫晶化方式都是晶核生長受擴散控制的初晶型或共晶型晶化,并且形核和長大速率隨時間減小;三種試樣的有效晶化激活能分別為448 kJ/mol、457 kJ/mol和333 kJ/mol。
[Abstract]:Because of the special atomic space arrangement, amorphous alloys have many better physical and chemical properties than metallic crystal materials, which make them have great application prospects in many fields such as sports products, aerospace, biological applications and so on. However, at room temperature, the amorphous alloy can obtain limited plasticity by shear, which makes it limited in practical application. The self-repair of the shear band of amorphous alloy can delay the expansion of the shear band. Therefore, it is of great theoretical and practical significance to study the self-repair behavior of the shear band of amorphous alloy. In this paper, Zr_ (65) Cu_ (15) Ni_ (12. 5) Al_ (7. 5) bulk amorphous alloys were used to study the self repair of shear bands by heat treatment in its subcooled liquid phase, and the effect of self repair of shear bands on the thermal properties of amorphous alloys was further studied by thermal analysis. The samples used in the experiment are as follows: as-cast samples (without any treatment of the prepared samples), pre-repair samples (the as-cast samples produced 2% compressive plastic deformation), and the repaired samples (self-repair of the pre-repair specimens). The self-repairing of shear bands on the surface of specimens under different heat treatment conditions was studied. The results showed that the shear bands of the samples were repaired at different temperatures of 633K 643K and 653K for 10 min,20 min and 30 min, respectively. When the repair temperature is the same, the extent of shear band repair becomes more obvious with the prolongation of repair time, and when the repair time is the same, with the increase of repair temperature, The results show that the samples repaired at 633K and 643K for 10 min are still amorphous, while the samples under other repair conditions are crystallized. The changes of thermal properties of the specimens before and after the shear band repair were studied by DSC. The results of DSC test showed that the changes of T _ (T _ g) of the samples repaired for 10 min at 650K during the continuous heating process were not obvious, and the changes of T _ (T) _ p and 螖 T _ Stax were obviously lower than those of the samples before and after the repair. The activation energies of glass transition of as-cast samples calculated by Kissinger method were 252 kJ/mol,263 kJ/mol and 270 kJ/mol, crystallization activation energies of 238 kJ/mol,255 kJ/mol and 296 kJ/mol., respectively. During isothermal crystallization, the inoculation time was shortened obviously. The range of Avrami exponent n of as-cast samples calculated by Johnson-Mehl-Avrami (JMA) method is 1.6981.991U 2.273N 2.446 and 2.152.30 respectively, which indicates that the isothermal crystallization mode is either primary or eutectic type controlled by diffusion of nucleation. And the nucleation and growth rates decreased with time, and the effective crystallization activation energies of the three samples were 448 kJ/mol,457 kJ/mol and 333 kJ/mol., respectively.
【學(xué)位授予單位】：煙臺大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG139.8
[Abstract]:Because of the special atomic space arrangement, amorphous alloys have many better physical and chemical properties than metallic crystal materials, which make them have great application prospects in many fields such as sports products, aerospace, biological applications and so on. However, at room temperature, the amorphous alloy can obtain limited plasticity by shear, which makes it limited in practical application. The self-repair of the shear band of amorphous alloy can delay the expansion of the shear band. Therefore, it is of great theoretical and practical significance to study the self-repair behavior of the shear band of amorphous alloy. In this paper, Zr_ (65) Cu_ (15) Ni_ (12. 5) Al_ (7. 5) bulk amorphous alloys were used to study the self repair of shear bands by heat treatment in its subcooled liquid phase, and the effect of self repair of shear bands on the thermal properties of amorphous alloys was further studied by thermal analysis. The samples used in the experiment are as follows: as-cast samples (without any treatment of the prepared samples), pre-repair samples (the as-cast samples produced 2% compressive plastic deformation), and the repaired samples (self-repair of the pre-repair specimens). The self-repairing of shear bands on the surface of specimens under different heat treatment conditions was studied. The results showed that the shear bands of the samples were repaired at different temperatures of 633K 643K and 653K for 10 min,20 min and 30 min, respectively. When the repair temperature is the same, the extent of shear band repair becomes more obvious with the prolongation of repair time, and when the repair time is the same, with the increase of repair temperature, The results show that the samples repaired at 633K and 643K for 10 min are still amorphous, while the samples under other repair conditions are crystallized. The changes of thermal properties of the specimens before and after the shear band repair were studied by DSC. The results of DSC test showed that the changes of T _ (T _ g) of the samples repaired for 10 min at 650K during the continuous heating process were not obvious, and the changes of T _ (T) _ p and 螖 T _ Stax were obviously lower than those of the samples before and after the repair. The activation energies of glass transition of as-cast samples calculated by Kissinger method were 252 kJ/mol,263 kJ/mol and 270 kJ/mol, crystallization activation energies of 238 kJ/mol,255 kJ/mol and 296 kJ/mol., respectively. During isothermal crystallization, the inoculation time was shortened obviously. The range of Avrami exponent n of as-cast samples calculated by Johnson-Mehl-Avrami (JMA) method is 1.6981.991U 2.273N 2.446 and 2.152.30 respectively, which indicates that the isothermal crystallization mode is either primary or eutectic type controlled by diffusion of nucleation. And the nucleation and growth rates decreased with time, and the effective crystallization activation energies of the three samples were 448 kJ/mol,457 kJ/mol and 333 kJ/mol., respectively.
【學(xué)位授予單位】：煙臺大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG139.8
【參考文獻】
相關(guān)期刊論文 前10條
1 高謙;堅增運;翟逸s，
本文編號：2224590
本文鏈接：http://sikaile.net/kejilunwen/jiagonggongyi/2224590.html
最近更新
教材專著
