面向等離子體Ti、TiN摻雜鎢基復(fù)合材料制備及其性能研究
發(fā)布時間：2018-11-13 18:10
【摘要】：鎢及其合金因其具有高熔點,良好的導(dǎo)熱性能,低濺射率等優(yōu)點被作為ITER中最具潛力的面向等離子體第一壁候選材料。但鎢及其合金存在低溫脆性、重結(jié)晶脆性及輻照脆性等問題,使其在實際應(yīng)用中受到限制。向鎢合金中添加第二相或合金元素是一種提高鎢合金綜合性能的手段之一。本文采用向鎢合金中添加納米氮化鈦(TiN)顆粒和氫化鈦(TiH2),通過機械球磨和放電等離子燒結(jié)的方法制備了W Ti TiN復(fù)合材料,研究了TiN添加量、機械球磨工藝和Ti添加量對W Ti TiN復(fù)合材料組織結(jié)構(gòu)和性能影響;同時,對W Ti TiN復(fù)合材料抗He~+輻照性能進行研究。主要研究結(jié)果如下:(1)采用機械合金化和放電等離子燒結(jié)制備W (0.5,1,2,4)wt.%TiN復(fù)合材料,TiN顆粒均勻分散在W基體中,對W基體產(chǎn)生彌散強化效果。隨著TiN含量增加,晶粒被明顯細化,出現(xiàn)穿晶斷裂特征以及顯微硬度不斷增加。W-2wt.%TiN復(fù)合材料具有最高致密度(98.73%)和抗拉強度(180MPa)。(2)隨著球磨時間的不斷增加,所制備的W-15wt.%Ti復(fù)合粉末重復(fù)著冷焊、斷裂、重焊過程,粉末的晶粒尺寸被細化至納米級別,在80小時球磨后檢測到非晶相存在;同時,TiH1.9分解并形成W-Ti固溶體。在燒結(jié)之后,隨著球磨時間增加,第二相分布更加均勻,并在球磨80小時的樣品中觀察到W和Ti相的中間區(qū)域存在過渡區(qū),其對應(yīng)于β(Ti,W)相。顯微硬度和導(dǎo)熱率隨著球磨時間延長而增加,80小時球磨粉末制備的復(fù)合材料具有最好性能。(3)通過在W TiN復(fù)合材料中添加不同含量的Ti元素,復(fù)合材料致密度和顯微硬度顯著提高,晶粒尺寸明顯細化至0.51μm。Ti含量為4wt.%時,復(fù)合材料性能最佳。在燒結(jié)期間,N可能擴散到其它Ti晶格中,從而形成Ti/TiN固溶體。此外,Ti添加改善了復(fù)合材料抗He~+輻射性能。沒有添加Ti的復(fù)合材料,輻照后TiN剝離,在晶界處留下孔洞且引起濺射腐蝕。當Ti含量為8wt.%時,沒有觀察第二相剝離,僅在W晶粒和富Ti相中都觀察到少量密度氣泡。
[Abstract]:Tungsten and its alloys are considered as the most promising candidate materials for plasma wall in ITER due to their high melting point, good thermal conductivity and low sputtering rate. However, the low temperature brittleness, recrystallization brittleness and irradiation brittleness of tungsten and its alloys are limited in practical application. Adding the second phase or alloy element to tungsten alloy is one of the ways to improve the comprehensive properties of tungsten alloy. In this paper, W Ti TiN composites were prepared by mechanical ball milling and spark plasma sintering by adding nano-titanium nitride (TiN) particles and titanium hydride (TiH2) into tungsten alloys. The amount of TiN was studied. The effects of mechanical ball milling and Ti addition on the microstructure and properties of W / Ti / TiN composites were investigated. At the same time, the radiation resistance of W Ti / TiN composites to He~ was studied. The main results are as follows: (1) wt.%TiN composites were prepared by mechanical alloying and spark plasma sintering. TiN particles were uniformly dispersed in W matrix, resulting in dispersion strengthening effect on W matrix. With the increase of TiN content, the grain size is obviously refined. The transgranular fracture characteristics and microhardness of W-2wt.%TiN composites are increasing. The W-2wt.%TiN composites have the highest density (98.73%) and tensile strength (180MPa). (2) with the increasing of milling time. The W-15wt.%Ti composite powder was prepared by repeated cold welding, fracture and rewelding. The grain size of the powder was refined to nanometer level, and the amorphous phase was detected after 80 hours ball milling. At the same time, TiH1.9 decomposes and forms W-Ti solid solution. After sintering, the distribution of the second phase became more uniform with the increase of milling time, and the transition region of W and Ti phase was observed in the sample of 80 hours ball milling, which corresponds to 尾 (Ti,W) phase. The microhardness and thermal conductivity increase with the increase of milling time, and the composites prepared by 80 hours ball milling powder have the best properties. (3) by adding different contents of Ti elements into W TiN composites, The densification and microhardness of the composites were significantly increased, and the properties of the composites were the best when the grain size was obviously refined to 4wt.% of 0. 51 渭 m.Ti. During sintering, N may diffuse into other Ti lattice and form Ti/TiN solid solution. In addition, the addition of Ti improves the radiation resistance of composites to He~. The composites without Ti can be stripped off by TiN after irradiation, leaving holes at grain boundaries and causing sputtering corrosion. When the content of Ti is 8 wt.%, the second phase peel is not observed, only a few density bubbles are observed in W grain and rich Ti phase.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33
[Abstract]:Tungsten and its alloys are considered as the most promising candidate materials for plasma wall in ITER due to their high melting point, good thermal conductivity and low sputtering rate. However, the low temperature brittleness, recrystallization brittleness and irradiation brittleness of tungsten and its alloys are limited in practical application. Adding the second phase or alloy element to tungsten alloy is one of the ways to improve the comprehensive properties of tungsten alloy. In this paper, W Ti TiN composites were prepared by mechanical ball milling and spark plasma sintering by adding nano-titanium nitride (TiN) particles and titanium hydride (TiH2) into tungsten alloys. The amount of TiN was studied. The effects of mechanical ball milling and Ti addition on the microstructure and properties of W / Ti / TiN composites were investigated. At the same time, the radiation resistance of W Ti / TiN composites to He~ was studied. The main results are as follows: (1) wt.%TiN composites were prepared by mechanical alloying and spark plasma sintering. TiN particles were uniformly dispersed in W matrix, resulting in dispersion strengthening effect on W matrix. With the increase of TiN content, the grain size is obviously refined. The transgranular fracture characteristics and microhardness of W-2wt.%TiN composites are increasing. The W-2wt.%TiN composites have the highest density (98.73%) and tensile strength (180MPa). (2) with the increasing of milling time. The W-15wt.%Ti composite powder was prepared by repeated cold welding, fracture and rewelding. The grain size of the powder was refined to nanometer level, and the amorphous phase was detected after 80 hours ball milling. At the same time, TiH1.9 decomposes and forms W-Ti solid solution. After sintering, the distribution of the second phase became more uniform with the increase of milling time, and the transition region of W and Ti phase was observed in the sample of 80 hours ball milling, which corresponds to 尾 (Ti,W) phase. The microhardness and thermal conductivity increase with the increase of milling time, and the composites prepared by 80 hours ball milling powder have the best properties. (3) by adding different contents of Ti elements into W TiN composites, The densification and microhardness of the composites were significantly increased, and the properties of the composites were the best when the grain size was obviously refined to 4wt.% of 0. 51 渭 m.Ti. During sintering, N may diffuse into other Ti lattice and form Ti/TiN solid solution. In addition, the addition of Ti improves the radiation resistance of composites to He~. The composites without Ti can be stripped off by TiN after irradiation, leaving holes at grain boundaries and causing sputtering corrosion. When the content of Ti is 8 wt.%, the second phase peel is not observed, only a few density bubbles are observed in W grain and rich Ti phase.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TB33
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