【摘要】：金屬玻璃擁有優(yōu)異的力學與物理性能,但其廣泛應用一直受制于其低的室溫塑性和差的成型能力。為改變這一現(xiàn)狀,本課題組基于Johnson發(fā)明的脈沖電流快速熱塑性成型法創(chuàng)新并發(fā)展出高流變成型方法(HRRF)。前期研究表明,HRRF法可顯著強化Zr_(48)Cu_(36)Al_8Ag_8塊體金屬玻璃(BMG)微觀結(jié)構(gòu)不均勻性,大幅提高其壓縮塑性。然而,關(guān)于該法顯著增加Zr基BMGs壓縮塑性作用規(guī)律的普遍性及其機理仍不清楚,同時,HRRF法對該類金屬玻璃的β弛豫、熱穩(wěn)定性、內(nèi)耗與弛豫行為的作用與規(guī)律也缺乏研究。本文以Zr_(48)Cu_(30)Al_8Ag_8Pd_6、Zr45(Cu_5/6Ag_(1/6))48Al7和Zr_(48)Cu_(36)Al_8Ag_8成分BMGs為研究對象,首先通過對金屬玻璃HRRF前后樣品進行壓縮實驗,并以SEM觀察其表面剪切帶和斷口形貌,以探索HRRF法對Zr基BMGs增塑作用、規(guī)律及其機理。再運用差示掃描量熱法(DSC),電阻和內(nèi)耗技術(shù)研究HRRF法對該類金屬玻璃β弛豫、熱穩(wěn)定性、內(nèi)耗與弛豫行為等的作用與規(guī)律,以期揭示HRRF方法的增塑作用機理及其相關(guān)伴隨現(xiàn)象,從而為克服BMGs脆性特征,拓展BMGs工程應用范圍提供科學與技術(shù)依據(jù)。主要成果與結(jié)論如下:1.Zr_(48)Cu_(30)Al_8Ag_8Pd_6和Zr45(Cu_5/6Ag_(1/6))48Al7玻璃HRRF前后樣品壓縮應力-應變曲線表明,HRRF后樣品壓縮塑性顯著提高,且曲線均呈現(xiàn)更明顯鋸齒波形,反映了HRRF法對Zr基BMGs增塑效果及引起流變行為的改變。壓縮樣品SEM照片揭示,HRRF后樣品表面剪切帶數(shù)量明顯增多,并伴隨明顯的交割、分叉的特征,同時其斷口處剪切脈狀花紋致密并出現(xiàn)數(shù)量眾多的液滴狀顆粒,表明了HRRF法對剪切帶形成與演化行為及微觀結(jié)構(gòu)不均勻性的改變作用。DSC結(jié)果顯示,HRRF法顯著增大樣品的放熱峰面積,表明該方法增多該類BMGs內(nèi)部自由體積數(shù)量。這些結(jié)果從塑性流變行為及微觀機制上揭示了該方法增塑的作用本質(zhì)。2.結(jié)合DSC手段,首次以電阻法探索了HRRF法對Zr_(48)Cu_(36)Al_8Ag_8金屬玻璃β弛豫及熱穩(wěn)定性作用規(guī)律。升溫速率10K/min驗證表明,電阻法所標定樣品的β弛豫開始溫度Tβ、一次晶化開始溫度T_(x-onset)及其區(qū)間等特征參數(shù)均與DSC結(jié)果相吻合。這證明,電阻法探索β弛豫及熱穩(wěn)定性的有效性。為獲得更詳細信息,進一步以升溫速率1K/min測試了約化電阻率曲線,結(jié)果表明,HRRF后樣品Tβ大幅提前,且β弛豫所致電阻率變化值Δρrel顯著增加,表明該方法顯著增強該金屬玻璃β弛豫強度。HRRF后T_(x-onset)滯后且晶化溫度區(qū)間ΔTx變寬,反映該方法提高了該金屬玻璃的熱穩(wěn)定性,這一結(jié)論得到不同溫度淬火樣品X衍射結(jié)果證實。3.Zr_(48)Cu_(36)Al_8Ag_8金屬玻璃HRRF前后樣品內(nèi)耗溫度譜揭示,隨著溫度的升高,HRRF前后樣品的內(nèi)耗均依次表現(xiàn)為線性緩慢增加、較快速非線性增加、急速上升和出現(xiàn)內(nèi)耗峰的不同變化階段;內(nèi)耗頻率譜上內(nèi)耗則依次表現(xiàn)為線性增大、先迅速減小后緩慢增加、先迅速下降后緩慢下降和出現(xiàn)內(nèi)耗峰。對比HRRF前后樣品的溫度譜圖可發(fā)現(xiàn),HRRF后樣品各加載頻率下的內(nèi)耗峰值與內(nèi)耗峰溫均明顯高于其相應HRRF前的;對比HRRF前后金屬玻璃相同頻率譜特征的溫度區(qū)間范圍可知,HRRF后樣品β弛豫開始、β弛豫向α弛豫轉(zhuǎn)變均在更低的溫度下發(fā)生,對應其原子或原子集團運動更加容易;而滿足晶化要求的原子結(jié)構(gòu)重排則變得困難,晶化轉(zhuǎn)變的難度加大。
[Abstract]:The metal glass has excellent mechanical and physical properties, but its wide application has been subject to its low room temperature plasticity and poor molding ability. In order to change the present situation, the research group has developed a high-rheological forming method (HRRF) based on the high-speed thermoplastic forming method of the pulse current of Johnson invention. The preliminary study shows that the HRRF method can significantly enhance the microstructure and the compression plasticity of the Zr _ (48) Cu _ (36) Al _ 8Ag _ 8 bulk metallic glass (BMG). However, the general principle and mechanism of the significant increase of the compression plasticity of Zr-based BMGs in this method are still not clear. At the same time, the thermal relaxation, thermal stability, internal friction and relaxation behavior of this kind of metal glass are not studied by the HRRF method. In this paper, the research object of Zr _ (48) Cu _ (30) Al _ 8Ag _ 8Pd _ 6, Zr45 (Cu _ 5/ 6Ag _ (1/6)) 48Al7 and Zr _ (48) Cu _ (36) Al _ 8Ag _ 8 component BMGs is studied, and the surface shear zone and fracture morphology of the metal glass HRRF are studied by means of SEM. By using differential scanning calorimetry (DSC), resistance and internal friction technique, the effects and rules of the HRR method on the relaxation, thermal stability, internal friction and relaxation behavior of this kind of metal glass are studied. And the application scope of the BMGs engineering is expanded to provide scientific and technical basis. The main results and conclusions are as follows: 1.Zr _ (48) Cu _ (30) Al _ 8Ag _ 8Pd _ 6 and Zr45 (Cu _ 5/ 6Ag _ (1/6))48-Al7 glass HRRF sample compression stress-strain curve show that the compression plasticity of the sample after HRRF is obviously improved, and the curve all presents a more obvious sawtooth waveform, which reflects the effect of HRRF on the plasticizing effect of Zr-based BMGs and the change of the rheological behavior. the sem photographs of the compressed samples revealed that the number of shear bands on the surface of the sample after hrf was significantly increased and accompanied by significant delivery, bifurcation characteristics, while the shear pulse pattern at the fracture was dense and a large number of droplet-like particles were present, The effects of HRRF on the formation and evolution of the shear band and the non-uniformity of the microstructure are shown. The DSC results show that the HRRF method significantly increases the heat release peak area of the sample, indicating that the method increases the number of free volumes within this kind of BMGs. These results reveal the effect of this method on the plastic rheological behavior and micro-mechanism. The relaxation and thermal stability of Zr _ (48) Cu _ (36) Al _ 8Ag _ 8 metal glass were investigated by means of resistance method with the means of DSC. The temperature rise rate of 10 K/ min shows that the initial temperature T _ (x-onset) and the interval of the primary crystallization start temperature T _ (x-onset) and its interval are consistent with the DSC results. The results show that the resistance method is effective for exploring the thermal relaxation and thermal stability. In order to obtain more detailed information, the approximate resistivity curve was further tested at a temperature-raising rate of 1 K/ min. The results show that after the HRRF, the temperature of the sample T is significantly advanced, and the value of the resistivity change due to the relaxation is significantly increased, indicating that the method significantly enhances the relaxation strength of the metal glass. The thermal stability of the metal glass is improved by the hysteresis of the T _ (x-onset) and the broadening of the temperature range of the crystallization temperature after the HRRF. The results of the X-ray diffraction of the sample with different temperature quenching show that the temperature profile of the sample in the front and back samples of the HRRF of the Zr _ (48) Cu _ (36) Al _ 8Ag _ 8 metal glass reveals that with the increase of the temperature, The internal friction of the samples before and after the HRRF is shown as a linear slow increase, a faster non-linear increase, a rapid increase and a different phase of the internal friction peak. The internal friction in the internal friction frequency spectrum is shown as a linear increase, and then slowly increases after the rapid decrease, And then the internal friction peak is slowly reduced and the internal friction peak appears after the rapid descent. The temperature profile of the samples before and after the HRRF can be found, and the peak of the internal friction and the temperature of the internal friction peak at each loading frequency of the HRRF sample are obviously higher than that of the corresponding HRRF; and the temperature range of the same frequency spectrum characteristic of the metal glass before and after the HRRF can be seen, and the thermal relaxation of the sample after the HRRF starts, The transition of the initial relaxation and the relaxation is at a lower temperature, and the movement of the atom or the atom group is easier; and the rearrangement of the atomic structure satisfying the crystallization requirement becomes difficult, and the difficulty of the crystallization transition is increased.
【學位授予單位】：合肥工業(yè)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(guān)期刊論文 前5條

1 汪衛(wèi)華;;非晶態(tài)物質(zhì)的本質(zhì)和特性[J];物理學進展;2013年05期

2 王麗芳;崔曉;黃中月;王知鷙;祖方遒;;電阻法探索Cu_(36)Zr_(48)Al_8Ag_8非晶晶化行為及熔體過熱對其GFA與熱穩(wěn)定性的影響[J];科學通報;2013年Z2期

3 汪衛(wèi)華;;金屬玻璃研究簡史[J];物理;2011年11期

4 楊開巍;水嘉鵬;朱震剛;;不同一級相變材料的內(nèi)耗峰形成機制[J];上海交通大學學報;2010年05期

5 劉軍民，，水嘉鵬;非晶態(tài)合金的結(jié)構(gòu)弛豫過程[J];金屬學報;1995年19期

相關(guān)博士學位論文 前2條

1 王麗芳;電阻和內(nèi)耗法探索Cu-Zr-Al-Ag系非晶合金熱穩(wěn)定性和晶化/弛豫行為與玻璃形成能力[D];合肥工業(yè)大學;2016年

2 崔曉;基于電子輸運/內(nèi)耗性質(zhì)及熔體狀態(tài)探索非晶合金GFA[D];合肥工業(yè)大學;2013年

本文編號：2507564