本文選題：激光噴丸 + vit1塊體非晶合金�。� 參考：《山東大學》2016年博士論文

【摘要】：非晶合金由于具有高耐磨、耐蝕性、高彈性極限、高強度以及優(yōu)良的磁性能等優(yōu)點,因而在多種領(lǐng)域均具有十分廣闊的應用前景。然而,非晶合金由于其獨特的短程有序、長程無序結(jié)構(gòu),致使其在室溫下的宏觀塑性近乎為零,成為制約其成形制造以及的工程應用關(guān)鍵瓶頸。因此,如何改善非晶合金的室溫塑性已經(jīng)成為材料研究領(lǐng)域迫切需要解決的問題。本文實驗采用Zr41.2Ti13.8Cu12.5Ni10Be22.5(vit1)塊體非晶合金,開展了激光噴丸熱效應、激光噴丸沖擊力效應,以及激光噴丸熱/力效應對非晶合金表面形貌、微觀組織結(jié)構(gòu)以及力學性能和耐腐蝕性的影響等研究工作。主要結(jié)論如下：(1)首先研究了熱效應為主的單點激光噴丸對非晶合金表面形貌的影響,探討了激光與非晶合金相互作用的過程和機理,通過表面張力波理論、Kelvin.Helmholtz不穩(wěn)定性機制以及Saffman-Taylor不穩(wěn)定性理論對噴丸邊緣區(qū)域形成的的周期性波紋以及指化現(xiàn)象進行了理論解釋；其次研究了圓環(huán)結(jié)構(gòu)直徑和波紋間距隨激光能量、脈沖次數(shù)的演變情況。研究結(jié)果表明,圓環(huán)結(jié)構(gòu)的直徑隨著激光能量和脈沖次數(shù)的增加近似呈線性增大,但脈沖次數(shù)大于10后圓環(huán)結(jié)構(gòu)的直徑增長趨勢放緩。波紋間距不隨激光能量的大小而改變,但隨著脈沖次數(shù)的增加逐漸增大。當能量為600 mJ,脈沖次數(shù)為200時,在噴丸區(qū)域還形成大量無規(guī)則分布的微裂紋。(2)系統(tǒng)研究了沖擊力效應為主的單點激光噴丸對非晶合金表面完整性的影響。首先研究了激光噴丸對非晶合金表面微觀組織結(jié)構(gòu)、光學形貌和粗糙度的影響,并對其影響機制進行了分析；其次研究了激光噴丸對非晶合金硬度的影響,分析了硬度變化的原因；最后對激光噴丸后非晶合金的表面微裂紋/剪切帶及其形成機制進行了分析。研究結(jié)果表明,非晶合金在激光噴丸處理后仍然保持了非晶態(tài)結(jié)構(gòu),但噴丸區(qū)域形成一個圓形微凹坑,且表面粗糙度增大,原因在于激光噴丸時形成的沖擊波壓力遠高于材料彈性極限,并且激光能量不均和吸收層表面的不平整,造成沖擊波壓力不均勻。隨著噴丸過程中激光能量的增加,非晶合金表面微凹坑的直徑和深度也呈現(xiàn)出逐漸增大的趨勢,同時表面粗糙度也越高。激光噴丸區(qū)域硬度降低,且噴丸中心區(qū)域硬度減小幅度最大,約為13%,分析表明激光噴丸塑性變形區(qū)域內(nèi)形成的大量剪切,由于應變軟化導致非晶合金硬度降低。在激光噴丸誘導的高壓沖擊波作用下,非晶合金試樣表面的剪切帶／微裂紋是通過孔洞的連接來實現(xiàn)的。(3)系統(tǒng)研究了多點激光噴丸對非晶合金微觀組織結(jié)構(gòu)和力學性能的影響規(guī)律。首先分析了等腰直角搭界方式下不同橫向搭接率對非晶合金表面粗糙度的影響；其次,采用優(yōu)化的工藝參數(shù)對非晶合金進行激光噴丸處理,研究了激光噴丸前后非晶合金微觀組織結(jié)構(gòu)的變化；最后通過三點彎曲實驗、單向壓縮實驗系統(tǒng)研究了激光噴丸對非晶合金室溫塑性的影響。研究結(jié)果表明,當橫向搭接率為29.3%時,激光噴丸后試樣表面粗糙度最小。多點激光噴丸后,非晶合金仍然保持非晶態(tài)結(jié)構(gòu),但在非晶合金內(nèi)產(chǎn)生了大量的自由體積。激光噴丸處理后非晶合金在三點彎曲過程中塑性變形撓度增大了1.83倍,分析表明塑性的增強得益于激光噴丸后非晶合金自由體積的增大,在后續(xù)變形中更易生成多重剪切帶。單向壓縮實驗表明激光噴丸非晶試樣具有明顯的尺寸效應,小尺寸塊體非晶合金試樣具有更高的壓縮強度和更優(yōu)異的塑性。(4)系統(tǒng)研究了多點激光噴丸熱/力效應對非晶合金微觀組織結(jié)構(gòu)和性能的影響。首先通過無吸收層激光噴丸(Laser shock peening without coating, LSPwC)工藝對非晶合金試樣表面進行噴丸處理,并對LSPwC處理后非晶合金表面的微觀組織結(jié)構(gòu)進行了分析；其次研究了LSPwC處理后非晶合金的室溫塑性；分析了激光噴丸熱/力效應對非晶合金塑性影響的機制；最后研究了LSPwC處理后非晶合金的納米硬度和耐蝕性。研究結(jié)果表明,LSPwC處理后非晶合金表面仍保持非晶特質(zhì),但在非晶合金熔融表層120μm以下檢測到分布均勻的晶化相。LSPwC處理后非晶合金塑性撓度增加了23%,分析表明在彎曲變形過程由LSPwC引起的非晶合金自由體積的增大、晶化相的產(chǎn)生以及表層復雜分布的殘余應力使得非晶合金的塑性增大,由LSPwC處理后產(chǎn)生的燒蝕坑導致非晶合金的塑性降低,但其對LSPwC處理后非晶合金塑性的影響并不占據(jù)主導地位。LSPwC處理后非晶合金納米硬度減小,但耐蝕性增強,并且采用吸收層的激光噴丸處理后的非晶合金耐蝕性更好。
[Abstract]:Because of its advantages of high abrasion resistance, corrosion resistance, high elasticity limit, high strength and excellent magnetic properties, amorphous alloys have a very broad application prospect in many fields. However, because of their unique short range order and long range disordered structure, the macroscopic plasticity at room temperature is almost zero, which restricts its formation. It is a key bottleneck in the engineering application of shape manufacturing and engineering. Therefore, how to improve the room temperature plasticity of amorphous alloys has become an urgent problem to be solved in the field of material research. In this paper, Zr41.2Ti13.8Cu12.5Ni10Be22.5 (vit1) bulk amorphous alloy was used to carry out the thermal effect of laser shot peening, the impact force effect of laser shot peening, and the laser shot peening heat. The main conclusions are as follows: (1) first, the effect of the single point laser shot peening on the surface morphology of amorphous alloy was first studied, and the process and mechanism of the interaction between laser and amorphous alloy were discussed. The Zhang Libo theory, the Kelvin.Helmholtz instability mechanism and the Saffman-Taylor instability theory explain the periodic ripples and the denying phenomena in the edge region of the shot peening. Secondly, the evolution of the ring structure diameter and the ripple spacing with the laser energy and the pulse number are studied. The diameter of the structure increases linearly with the increase of the laser energy and the number of pulses, but the growth trend of the ring structure is slowed down after the number of pulses is greater than 10. The wave spacing does not change with the size of the laser energy, but increases with the increase of the number of pulses. When the energy is 600 mJ and the number of pulses is 200, it is also formed in the shot peening area. A large number of irregular microcracks. (2) the effect of single point laser shot peening on the surface integrity of amorphous alloy was studied systematically. First, the effect of laser shot peening on the microstructure, optical morphology and roughness of amorphous alloy surface was studied, and the mechanism of its effect was analyzed. Secondly, the laser spray was studied. The influence of the pill on the hardness of amorphous alloy was analyzed, and the reasons for the change of hardness were analyzed. Finally, the surface micro crack / shear band and the formation mechanism of the amorphous alloy after the laser shot peening were analyzed. The results showed that the amorphous alloy still retained the amorphous structure after the laser shot peening, but the shot peening area formed a circular micropits. The surface roughness increases because the shock wave pressure formed by the laser shot peening is much higher than the elastic limit of the material, and the uneven laser energy and the surface of the absorption layer make the shock wave pressure uneven. With the increase of the laser energy in the shot peening, the diameter and depth of the surface micro pits of the amorphous alloy surface also increase gradually. At the same time the surface roughness is also higher. The hardness of the laser shot peening area decreases and the hardness of the shot peening center is reduced to about 13%. The analysis shows that a large amount of shear formed in the plastic deformation region of the laser shot peening is caused by the strain softening. The shear band / micro crack on the surface of the alloy sample is realized through the connection of holes. (3) the influence of multi point laser shot peening on the microstructure and mechanical properties of amorphous alloy is systematically studied. First, the influence of different transverse lap ratio on the surface roughness of amorphous alloy under the isosceles right angle lap mode is analyzed. Secondly, the application of the method is to analyze the influence of the different transverse lap ratio on the surface roughness of the amorphous alloy. The optimized process parameters of the amorphous alloy were treated by laser shot peening, and the microstructure of the amorphous alloy before and after the laser shot peening was studied. Finally, the effect of laser shot peening on the room temperature plasticity of amorphous alloy was studied by three point bending experiment and unidirectional compression experimental system. The results showed that when the transverse lap rate was 29.3%, laser After shot peening, the surface roughness of the sample is minimal. After the shot peening, the amorphous alloy remains amorphous, but a large amount of free volume is produced in the amorphous alloy. The deformation deflection of the amorphous alloy after the laser shot peening is 1.83 times higher than that of the three point bending process. The analysis shows that the plasticity is enhanced by the laser shot peening. The increase of the free volume of the crystalline alloy makes it easier to produce multiple shear bands in the subsequent deformation. The unidirectional compression test shows that the amorphous samples of the laser shot peening have obvious size effect, and the small size bulk amorphous alloy samples have higher compressive strength and more excellent plasticity. (4) the thermal / force effect of multi point laser shot peening on the amorphous alloy has been studied systematically. The influence of microstructure and properties of the amorphous alloy was first shot by Laser shock peening without coating (LSPwC) technology, and the microstructure of the amorphous alloy surface after LSPwC treatment was analyzed. Secondly, the room temperature plasticity of the amorphous alloy after LSPwC treatment was studied. The mechanism of the effect of laser shot peening heat / force on the plasticity of amorphous alloy was analyzed. The nano hardness and corrosion resistance of the amorphous alloy after LSPwC treatment were studied. The results showed that the amorphous alloy remained amorphous on the surface of the amorphous alloy after LSPwC treatment, but the homogeneous crystalline phase.LS was detected below 120 u m in the melt surface of the amorphous alloy. The plastic deflection of amorphous alloy after PwC treatment increased by 23%. The analysis showed that the free volume of amorphous alloy increased by LSPwC, the production of crystalline phase and the residual stress in the complex surface of the surface made the plasticity of amorphous alloy increase, and the ablative pit produced by the LSPwC treatment resulted in the reduction of the plasticity of amorphous alloy, but it also resulted in the reduction of the plasticity of amorphous alloy. The effect of LSPwC treatment on the plastic properties of amorphous alloys does not occupy the dominant position of.LSPwC treatment, the hardness of amorphous alloy decreases, but the corrosion resistance is enhanced, and the corrosion resistance of amorphous alloy after the laser shot peening treatment is better.
【學位授予單位】：山東大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TG139.8;TG668

【參考文獻】

相關(guān)期刊論文 前1條

1 張永康;周立春;任旭東;李楊;魯金忠;;激光沖擊TC4殘余應力場的試驗及有限元分析[J];江蘇大學學報(自然科學版);2009年01期

相關(guān)碩士學位論文 前1條

1 石慧崗;非晶合金室溫下力學行為的理論分析與數(shù)值模擬[D];山東大學;2012年

，

本文編號：1957686