Ti3SiC2块儿状陶瓷的微观组织及其耐损坏机制论文翻译.doc

Microstructure and mechanism of damage tolerance for Ti3SiC2 bulk块儿状 ceramicsTi3SiC2块儿状陶瓷的微观组织及其耐损坏机制AbstractTitanium silicon carbide (Ti3SiC2) is a damage tolerance material that is expected to be used in a number of high temperature applications. Ti3SiC2陶瓷是在高温应用中使用的损伤容限材料。 In this work, the microstructure and damage tolerance mechanism of Ti3SiC2 is investigated. 在这项工作中，将研究Ti3SiC2的微观结构和损伤耐受机制。The result demonstrated that the Ti3SiC2 ceramics prepared by the in-situ hot pressing/solid-liquid reaction process had a dual microstructure, i.e., large laminated grains were distributed 分散within small equiaxial grains. 结果表明，Ti3SiC2的准备原位热压/固 - 液反应过程的陶瓷双微观结构，即，大型层压颗粒被小的等轴晶粒分散开来。 This microstructure is analogous to that of platelets薄片 reinforced ceramic matrix composites. The bending test using single-edge-notched-beam specimens revealed that Ti3SiC2 was a damage tolerance material. 该组织类似于增强陶瓷基复合材料薄片。采用单边缘缺口梁试样的弯曲试验表明Ti3SiC2陶瓷损伤容限材料。The damage tolerance mechanisms for Ti3SiC2 are basal plane slip, grain buckling, crack deflection, crack branching, pull-out and delamination of the laminated grains. Ti3SiC2陶瓷的损伤耐受机制有基面滑移，晶粒弯曲，裂纹偏转，裂纹分支，拉出和夹层颗粒分层。Key wordsTi3SiC2 Microstructure Damage mechanism Crystallite shapeIntroductionTitanium silicon carbide (Ti3SiC2) is a novel ceramic material, which combines the merits of both metals and ceramics. Ti3SiC2陶瓷是一种新型的陶瓷材料，它结合了金属和陶瓷的优点。 It is a good thermal and electrical conductor, not susceptible to thermal shock, and easy to machine with conventional tools. 这是一个很好的热导体和电导体，不容易受到热冲击，容易用传统工具加工。The unit cell of Ti3SiC2 bulk materials has stimulated the research in understanding the behavior of Ti3SiC2. Ti3SiC2块状陶瓷的晶胞激发了工作人员对Ti3SiC2的行为理解研究.Barsoum et al synthesized Ti3SiC2 bulk ceramics by reactive hot pressing method. The flexure strength of the material made by this method was 290 MPa at room temperature. Barsoum等反应热压法合成Ti3SiC2的散装陶瓷，用这种方法制成的材料在室温抗弯强度为290兆帕。Zhou et al developed an in-situ hot pressing/solid-liquid process for the synthesis of Ti3SiC2. 周某等人开发的原位热压法合成Ti3SiC2陶瓷。 The materials prepared by this method showed flexure strength of 480 MPa and fracture toughness of 8.55 MPa.m1/2. 用这种方法制备的材料，其抗弯强度为480兆帕，断裂韧性的8.55 MPa.m1/2。Gota and Hirai, Lis et al, El-Raghy et al measured the Vickers hardness for Ti3SiC2 and they demonstrated that the Vickers hardness decreased with increasing load asymptotically approached 4 GPa at highest load. Gota and Hirai, Lis et al, El-Raghy等人，为Ti3SiC2作维氏硬度测量，他们证明了其维氏硬度会随着接近（4 GPa）最高负荷而下降。El-Raghy et al also investigated the damage around the indentation and found that no indentation cracks were observed even at loads as high as 300N. EL-Raghy等还考察了周围的压痕损伤和发现，观察无压痕裂纹甚至可承受300N高负荷。Further more, the low value of the ratio of hardness to Youngs modulus, H/E=0.013, implies that the mechanical behavior of Ti3SiC2 should be somewhat similar to ductile soft metals. 此外，硬度与杨氏模量的比值低（H / E= 0.013）意味着Ti3SiC2的性能应该有点类似韧性软金属。 Despite of the fact that damage mechanisms of Ti3SiC2 ceramics have been investigated in a number of Vickers indentation tests, and energy absorbing mechanisms like delamination, crack deflection, grain push-out were proposed, the microstructure features and the damage tolerance mechanisms are still not fully understood. 尽管Ti3SiC2的陶瓷的损伤机制已通过Vickers压痕测试和能量吸收机制（如分层，裂纹偏转）的事实，然而微观结构特点和损伤容限机制还没有完全理解。The purpose of the present investigation is to understand the microstructure characteristics and the damage tolerance mechanisms for Ti3SiC2. 本次调查的目的是理解Ti3SiC2的微观结构特征和损伤容限机制。The microstructure features of Ti3SiC2 was investigated by scanning electron microscopy and compared to the computer simulated crystallite shape for Ti3SiC2. Ti3SiC2的微观结构特征已经通过扫描电子显微镜进行了研究，并且也同Ti3SiC2的计算机模拟晶粒的形状进行了对比。For the study of the damage tolerance mechanisms, single-edge-notched-beam (SENB) specimen was used. 为了损伤耐受机制，单边缺口梁（SENB）标本将投入使用。 The load-displacement curves during the three point bending test of SENB specimen were recorded. 单边切口梁试样在三点弯曲试验的载荷 - 位移曲线同样被记录下来。 The crack propagation path in the SENB specimen after unloading was examined in a scanning electron microscope. 取下单边切口梁试样，用扫描电子显微镜对其裂纹扩展路径进行观察。ExperimentalThe material used in the present work is bulk Ti3SiC2 material, TSCZS510, which is prepared by the in-situ/solid-liquid reaction process. 在目前的工作中所使用的材料是散装Ti3SiC2材料，TSCZS510，这是由的固-液反应过程制备出来的。 Briefly, the material was made in the following procedure. Ti, Si, and graphite powders were mixed and milled in a polypropylene jar for ten hours. 简单地说，材料是经以下过程制备出来的。钛，硅，石墨粉末混合，并在聚丙烯罐子里磨十个小时。After ball milling, the powders were cold-pressed into discs of 50 mm in diameter under a pressure of 5 MPa and then put in a graphite die. 球磨后，粉末将在5兆帕的压力下被冷压进直径为50毫米的圆盘中，然后将其装入在石墨模具。The in-situ hot pressing/solid-liquid reaction was conducted under a flowing argon atmosphere in a furnace using graphite as heating element.这种原位热压反应是在氩气气氛下进行的，并以石墨炉作为加热元件。 The material, TSCZS510, was hot pressed at 1550 under a pressure of 40 MPa for 60 min. 而后TSCZS510材料会在温度为1550、压力为40兆帕条件下热压60分钟。 Details for the in-situ hot pressing/solid-liquid reaction process have been described in our previous paper. 原位热压/固 - 液反应过程的详细信息已在我们以前的文件中有过具体描述。The Ti3SiC2 content in TSCZS510 is 93 wt, which was calculated using the Rietveld method and a DBWS program from Cerius computational program for material research (Molecular Simulation Inc., USA). TSCZS510 中的Ti3SiC2的含量为93，这是使用Rietveld方法和从Cerius材料研究的计算程序（分子模拟公司，美国）获得的DBWS方案中计算出来的。The Microstructure of Ti3SiC2 material was studied in scanning electron microscopy. 这之后就可以使用扫描电子显微镜研究Ti3SiC2材料的微观结构。 Crystallite shape of Ti3SiC2 was generated using a Morphology program based on Donnay-Harker theory in Cerius computational program for material research (Molecular Simulation Inc., USA). Ti3SiC2的晶粒形状是在使用基于Cerius材料研究的计算程序（分子模拟公司，美国）中Donnay-Harker理论的形态方案的基础上产生的。 single-edge-notched-beam (SENB) specimens were used in this work for the investigation of damage tolerance mechanism. 在这项工作中，单边缺口梁（SENB）标本被用作损伤耐受机制调查。The samples were electrical discharge machined into rectangular bars of 3636 mm3 in size. 对样品进行了电火花加工成大小3636 mm3的长方形。 The notch width was 0.1 mm. The bending tests were conducted in a Shenck universal testing machine. 缺口宽度为0.1毫米，弯曲试验会在Shenck万能试验机进行。The crosshead displacement rate was selected as 0.05 mm/min.滑移位移速率设定为0.05毫米/分钟。The load versus displacement during the loading and unloading of the SENB specimen was monitored.单边切口梁试样的加载和卸载过程中的负载与位移同样得到了监测。The crack propagation path in the SENB specimen after unloading was examined in a S-360 scanning electron microscope. 之后用S-360型扫描电子显微镜对卸货后的单边切口梁试样的裂纹扩展路径进行检查。Result and discussionThe microstructure of Ti3SiC2 ceramics (TSCZS510) prepared by the in-situ hot pressing/solid- quid reaction process is shown in Fig. 1. 如图1，,为通过原位热压/液固反应过程制得的Ti3SiC2材料的显微组织。The micrograph was taken from the fractured surface and was viewed in the direction perpendicular to the hot pressing axis. 这张显微图片是从断面拍摄的，且其拍摄方向热压轴的垂直方向。 It is seen from the SEM micrograph shown in Fig. 1 that the material consists of two kinds of grains, i.e., large laminated grains and small equiaxial grains are 20-25 m in diameter and 5-8 m in thickness, while the small equiaxial grains are 3-5 m in size. 从SEM拍摄的图1中看到，材料试样中包括两种晶粒，即大型片层晶粒的直径为20-25微米，厚度为5-8微米，而小的等轴晶粒大小为3-5微米。 Careful analysis of Fig. 1, we can find that the laminated grains are composed of a string of thin platelets. 仔细分析图1，我们可以发现，层状晶粒是有由一串薄片组成的。The cross section of the platelets is hexagonal as marked H in Fig. 1. 薄片的横截面是六角形，如图1中标注H的地方。 To understand the microstructure features of Ti3SiC2, we used Cerius computational program based on the theory of Donnay-Harker to generate the crystallite shape of Ti3SiC2. 为了了解Ti3SiC2的微观结构特征，基于Donnay-Harker理论，我们运用Cerius计算程序生成Ti3SiC2的晶粒形状我们运用Cerius计算程序。 Briefly, Donnay-Harker method defines the surface F, which will grow at the slowest rate and hence will be of highest morphological importance in crystal morphology. 简言之，Donnay-Harker方法定义了曲面F，它将以最慢的速度增长，因此这将在晶体形态结构方面具有重要意义。According to Donnay-Harker theory, the crystallite shape of Ti3SiC2 is determined by the relative growth rate on (002), (100) and (101) planes. 根据Donnay-Harker理论，Ti3SiC2的晶粒形状是由（002）（100）和（101）面的相对增长率决定的。If the growth rate on (101) face is the fastest, (002) and (100) faces with relatively slow growth rate are important and will determine the morphology of Ti3SiC2. 如果（101）面的增长速度是最快的，（002）和（100）与相对缓慢的增长速度就显得很重要，并将决定Ti3SiC2的形态。If the relative growth rate on (002), (100) and (101) faces are equivalent, the simulated crystallite shape is a polyhedral as shown in Fig. 2(b) and Fig. 2(c). 如果（002）（100）和（101）面的相对增长率是相等的，模拟晶粒的形状是如图2（b）和图2（c）所示的多面体。 These polyhedral crystallite shapes correspond to the equiaxial grains in Fig. 1. 这些多面体晶粒形状对应图1中的等轴晶粒。Thus the microstructure of bulk ceramics can be described as laminated grains consisting of a string of thin hexagonal slices distributed in equiaxial polyhedral grains. 因此块状Ti3SiC2的陶瓷的微观结构可以描述为，由一串六角形薄片组成的层状晶粒，且这些分散在等轴多面体晶粒中。 This microstructure is quite analogous to that of platelets reinforced ceramic matrix composites and improved fracture resistance is expected in this material. 这个组织是相当类似的薄片增强陶瓷基复合材料，这种材料有望提高抗断裂强度。Mechanism of damage tolerance1.Microstructure The contact damage of Ti3SiC2 has been investigated in early works and delamination, crack deflection, grain buckling, grain pull-out, and grain push-out were considered as the main energy absorbing mechanism for Ti3SiC2. Ti3SiC2的接触损伤在早期的作品已被调查，且分层，裂纹偏转，晶粒弯曲，晶粒拉出，晶粒推出被认为是Ti3SiC2的主要能量吸收机制。In this work, we investigated the damage tolerance mechanism using the single-edge-notched-beam specimen. 在这项工作中，我们调查采用单边缘缺口梁试样的损伤耐受机制。It is seen from Fig. 3 that the load-displacement curve is deviated from liner-elastic behavior, which is normal for brittle ceramic materials, the SENB specimen of Ti3SiC2 is a damage tolerance material.从图3可以看出，载荷-位移曲线偏离线弹性行为，这对于脆性陶瓷材料来说是正常的，Ti3SiC2的SENB标本是损伤容限材料。To understand the mechanism of damage tolerance for Ti3SiC2，the crack propagation path was examined in scanning electron microscopy. 要了解Ti3SiC2的损伤容限机制,，现通过扫描电子显微镜对裂纹扩展路径进行了检查。Figure 4 shows the crack propagation paths for the single-edge-notched-beam specimen after unloading. 图4显示了在卸货后的单边缺口梁试样的裂纹扩展路径。The arrows in the left low magnification micrographs of Fig. 4(a) and Fig. 4(b) show the direction of crack propagation. 在低倍率显微图4（a）和图4（b）左面的箭头显示了裂纹扩展的方向。Crack deflection can be deserved in Fig.4 and the crack propagation path show typical zigzag features. 图4显示了裂纹偏转，并且裂纹扩展路径显示出典型的锯齿状。Crack branching can also be identified as marked BC in the left low magnification micrograph of Fig. 4(a). 裂纹分支还可以在标示在图的左边低倍率显微图4（a）中的BC处显示出来。 In the high magnification micrograph of Fig. 4(a), which was taken from the rectangular area in the left micrograph, both pull-out and delamination of laminated grains are clearly shown. 在高倍率显微镜图4（a）中，在左边的显微图的矩形区域中，被同时拉出和脱层的层状颗粒清楚地显现出来。 In the high magnification micrograph on the right side of Fig. 4(b), evidence of grain pull-out and delaminating of the laminated grains can also be seen. 在上图右侧的高倍率显微图4（b）中，被同时拉出和脱层的层状颗粒也可以看出。 As we discussed in the above section that Ti3SiC2 has a dual microstructure, which is analogous to that of platelets reinforced ceramic matrix composites. 正如我们在上一节讨论了Ti3SiC2的具有双重的微观结构，这是类似于薄片增强陶瓷基复合材料。The mechanism for improved toughness of platelets rainforced ceramics matrix composite was investigated extensively.改善薄片增强陶瓷基复合材料韧性的机制正在被广泛调查。 Crack deflection, crack bridging, and platelet pull-out were considered as the main mechanism for the improved fracture resistance of platelets reinforced ceramics matrix composites. 裂纹偏转，裂纹桥接和晶粒薄片拉出被认为是改善薄片增强陶瓷基复合材料的抗断裂强度的主要机制。As for Ti3SiC2, because of the specific structure characteristics a