TiC-Al体系的燃烧反应合成

采用整体加热法对Ｔｉ、Ｃ和Ａ１三种粉末混合料的压坯进行燃烧反应合成，研究了升温速度及Ａｌ含量对反应过程及反应产物微观形貌和相组成的影响，探讨了在Ａ１基中ＴｉＣ粒子的形成机理。对Ｔｉ－Ｃ－Ａｌ体系反应物进行的差热分析（ＤＴＡ）及对产物进行的Ｘ射线衍射分析（ＸＲＤ）和扫描电镜（ＳＥＭ）观察的结果表明，在热爆反应合成过程中，首先是Ｔｉ与Ａｌ反应形成Ｔｉ与Ａｌ的化合物，放出热量，随后促使Ｔｉ和Ｃ的放热反应发生，合成ＴｉＣ时放出的高热使Ｔｉ与Ａｌ的化合物分解，从而使反应产物中只有ＴｉＣ和Ａｌ两相存在；升温速度及Ａｌ含量只有超过一定值时，该体系才能在较低温度发生热爆反应；体系中Ａｌ含量的增加会使合成ＴｉＣ颗粒尺寸变小，当Ａｌ含量从１０升至５０ｗｔ％时，其粒度范围为５μｍ～０．５μｍ。     

Al—8Fe—3Ti急冷合金的组织稳定性

本文研究了Ａｌ－８Ｆｅ－３Ｔｉ急冷合金中的亚稳相结构及合金在退火过程中组织和性能的变化。结果表明：合金中存在ＡｌｍＦｅ，Ａｌ６Ｆｅ及“Ｖ”相，另外还有一种新发现的富Ｔｉ相，合金具有较高的热稳定性。     

高铝锌基合金的变质处理及细化机理的研究

用Ｋ２ＴｉＦ６、ＫＢＦ４、ＲＥ分别或对ＺＡ２７合金变质处理。试验表明：在砂铸情况下,用Ｋ２ＴｉＦ６、ＫＢＦ４、ＲＥ进行变质处理是提高ＺＡ２７合金塑韧性的有效方法,其中以Ｋ２ＴｉＦ６＋ＫＢＦ４的效果最好。此外,对变质处理细化晶粒的机理进行了研究,研究表明：ＴｉＡｌ３、ＡｌＢ２、ＡｌＣｅ、Ａｌ２Ｃｅ等可作为α相生核的衬底,显著细化α相。     

Mn对Fe3Al金属间化合物不同温度下拉伸性能的影响

探讨了不同Ｍｎ含量对Ｆｅ３Ａｌ金属间化合物在２５～８００℃下拉伸性能的影响；并就Ｍｎ对Ｆｅ３Ａｌ合金化后的组织变化以及其对拉伸性能与断裂特征的影响进行了分析，结果表明，由于Ｍｎ对Ｆｅ３Ａｌ的合金化，而引入的具有面心立方有序结构的近Ｌ１２γ相，对Ｆｅ３Ａｌ的组织结构及拉伸性能产生了很大影响；随着Ｍｎ含量的增加，合金中ＤＯ３相的有序度降低；当Ｍｎ加入量适当时，可显著提高Ｆｅ３Ａｌ的室温强度和塑性，及合金的中高温塑性，但中高温强度衰减较大；总的说来，１０％Ｍｎ合金其塑性显著提高，室温强度大幅度提高，中高温强度与Ｆｅ３Ａｌ相当．     

铝热法合成TiB2—Al2O3系陶瓷原料反应机理

通过Ａｌ，Ｂ２Ｏ３和ＴｉＯ２体系的热力学分析指出了铝热法合成ＴｉＢ２的可能性，通过各种不同条件下反应过程的差热实验，Ｘ射线衍射等实验分析，对该体系的反应机理有了较系统深入的认识，得出：利用Ａｌ，Ｂ２Ｏ３和ＴｉＯ２（锐钛砂）在氩气中以较低的温度可合成出现纯的ＴｉＢ２及Ａｌ２Ｏ３陶瓷原料。     

Al—8Fe－3Ti急冷合金的组织稳定性

本文研究了Ａｌ－８Ｆｅ－３Ｔｉ急冷合金中的亚稳相结构及合金在退火过程中组织和性能的变化．结果表明：合金中存在ＡｌｍＦｅ、Ａｌ６Ｆｅ及“Ｖ”相，另外还有一种新发现的富Ｔｉ相。合金具有效高的热稳定性。     

Al2O3—TiC和Al2O3—TiB2的热力学分析

从理论上对铝热剂燃烧合成复相陶瓷Ａｌ２Ｏ３－ＴｉＣ和Ａｌ２Ｏ３－ＴｉＢ２的绝热温度及产物中Ａｌ２Ｏ３的熔经率进行了研究。随着预热温度的升高或稀释剂含量的降低,反应体系的绝热温度升高,但在２３０３Ｋ处均出现一个平台,其原因是Ａｌ２Ｏ３的熔化率不固定,在０－１之间变化,随预热温度的升高,燃烧反应能够自我维持的临界稀释剂的添加量也增多。     

Ti／TiAl复合材料界面与弯曲性能的研究

实测了单相γ－ＴｉＡｌ合金和塑性纤维韧化γ－ＴｉＡｌ金属间化合物复合材料的弯曲性能；利用ｘ射线衍射仪、光学显微镜，扫描电镜分析了Ｔｉ／ＴｉＡｌ复合材料的组织结构和界面，并研究了复合材料的界面和弯曲性能的关系．结果表明：Ｔｉ／ＴｉＡｌ复合材料的弯曲强度明显提高，但挠度提高不明显，界面厚度达３０ｕｍ，界面上有Ｔｉ２Ａｌ，Ｔｉ３Ａｌ等不同的反应产物存在。     

液相接触法生成TiAl3晶须的机理分析

在分析液相接触反应生成ＴｉＢ２颗粒机制时,发现反应块表面存在一些ＴｉＡｌ３＾８昌须。本文用ＳＥＭ分析了反应温度对ＴｉＡｌ３晶须形貌的影响,讨论了ＴｉＡｌ３晶须的生长机理结果表明：ＴｉＡｌ３晶须的长径比随反应温度升高而减少;ＴｉＡｌ３的晶须的生长机理为ＶＬＳ机制,但在晶须生长过程中触媒液滴里的Ｔｉ参与了反应,这与一般的晶须生长ＶＬＳ机理有所不同。     

微量B,Mg对TiAl金属间化合物热变形行为的影响

在１２７３～１５２３Ｋ的温度和１０－３～１００ｓ－１的应变速率范围内研究了微量元素Ｂ，Ｍｇ对固溶有Ｃｒ，Ｖ合金元素的ＴｉＡｌ金属间化合物热变形性能的影响，计算并建立了相应的热变形方程和热加工图，确定了实验合金的动态再结晶峰应力．结果表明：Ｂ，Ｍｇ的加入提高了ＴｉＡｌＣｒＶ合金的形变激活能，尤其是Ｍｇ的加入能显著改善ＴｉＡｌＣｒＶ金属间化合物的热加工性能．     

Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy

The performance of Al-Ti-C master alloy in refining Al-10Mg and Al-5Cu alloys was studied by using electron probe micro-analyzer （EPMA） and X-ray diffractometer （XRD） analysis. The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds. Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading. However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti（Al, Cu）2, which is responsible for the refinement fading in Al-5Cu alloy. These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.     

Effects of HIPing pressure on microstructures and properties of TiAl alloy

ＴｉＡｌａｌｌｏｙｉｓａｃａｎｄｉｄａｔｅｍａｔｅｒｉａｌｆｏｒａｄｖａｎｃｅｄａｅｒｏｓｐａｃｅａｉｒｆｒａｍｅｂｅｃａｕｓｅｏｆｉｔｓｌｏｗｄｅｎｓｉｔｙ ,ｇｏｏｄｏｘｉｄａ ｔｉｏｎｒｅｓｉｓｔａｎｃｅａｎｄｈｉｇｈｍｅｃｈａｎｉｃａｌｓｔｒｅｎｇｔｈａｔｈｉｇｈｔｅｍ ｐｅｒａｔｕｒｅ.Ｈｏｗｅｖｅｒ,ｉｔｓｌｏｗｅｒｔｅｎｓｉｌｅｄｕｃｔｉｌｉｔｙａｔａｍｂｉｅｎｔｔｅｍｐｅｒａｔｕｒｅｉｓｈｉｎｄｅｒｉｎｇｉｔｆｒｏｍｂｅｉｎｇｗｉｄｅｌｙｕｓｅｄ[1,2 ] .Ｔｏｉｍｐｒｏｖｅｔｈｅｓｅｍｅ…     

Grain Refining Performance of SHS Al—50TiC Master Alloys for Commercially pure Aluminum

An Al-50wt^TiC composite was directly synthesized by self-propagating high-temperature synthesis(SHS) technology,and then was used as a grain refining master alloy for commercially pure aluminun.The microstructure and grain refining performance of the synthesized master alloy were emphatically investigated.The SHS master alloy only ocntained submicron TiC particles except for Al matrix.Moreover,TiC particles were relatively free of agglomeration.Grain refining tests show that adding only 0.1wt^ of the master alloys to the aluminum melt could transform the sturcture of the solidified samples from coarse columnar grains to fine almost 1.5h at 1003K.Therefore,it is concluded that the SHS master alloy is an effective grain refiner for aluminum and its alloys,and that it is highly resistant to the grain refining fading encountered with most grain refiners.     

Fabrication of Dense Ultrafine TiAl Alloys by Spark Plasma Synthesis from Mechanically Activiated Powders

Powder of Ti-46at%Al alloy was synthesized through mechanical activation（MA） and then sintered and concurrently consolidated in a short sintering time of 900 s by using a spark plasma sintering（SPS） process. The XRD and SEM profiles show that the microstructures of TiAl alloys contained γ TiAl and small amount α-2 Ti3Al phase, whose amount can be controlled by the sintering temperature. The compacts retained the original fine-grained fully densified bodies by avoiding an excessively high sintering temperature. The alloys sintered at higher temperature with this process showed a coarser microstructure. So it is possible to produce dense nanostructured TiAl alloys by mechanically activated spark plasma sintering （MASPS） within a very short period of time.     

Preparation of TiAl/Al_2O_3 composites by combustion synthesis

0　ＩＮＴＲＯＤＵＣＴＩＯＮＴｉｔａｎｉｕｍａｌｕｍｉｎｉｄｅｓｂａｓｅｄｏｎＴｉＡｌｈａｖｅｅｘｃｅｌ ｌｅｎｔｐｏｔｅｎｔｉａｌｔｏｔａｋｅｔｈｅｐｌａｃｅｏｆｃｏｎｖｅｎｔｉｏｎａｌｔｉｔａｎｉ ｕｍａｎｄｎｉｃｋｅｌａｌｌｏｙｓｉｎａｄｖａｎｃｅｄｓｐａｃｅｃｒａｆｔｄｕｅｔｏｔｈｅｉｒｌｏｗｄｅｎｓｉｔｙ ,ｇｏｏｄｅｌｅｖａｔｅｄ ｔｅｍｐｅｒａｔｕｒｅｓｔｒｅｎｇｔｈａｎｄｈｉｇｈｒｅｓｉｓｔａｎｃｅｔｏｏｘｉｄａｔｉｏｎ[1～ 3] .Ｈｏｗｅｖｅｒ ,ｔｈｅｗａｙｔｏｐｒａｃｔｉｃａｌａｐｐ…     

THE PROCESS AND MECHANISM OF TiAl－BASED ALLOY SYNTHESIZED FROM Ti AND AlP OWDERS

ＴＨＥＰＲＯＣＥＳＳＡＮＤＭＥＣＨＡＮＩＳＭＯＦＴｉＡｌ－ＢＡＳＥＤＡＬＬＯＹＳＹＮＴＨＥＳＩＺＥＤＦＲＯＭＴｉＡＮＤＡｌＰＯＷＤＥＲＳＸｉｏｎＡｘＸｉａｎｙ；ＨｕａｎｇＢａｉｙｕｎ（ＰｏｗｄｅｒＭｅｔａｌｌｕｒｇｙＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｉｅ...     

A1TiCCeP对Al-30％Si合金初晶硅相的变质效果研究

借助SEM与XRD分析手段,对自制的AITiCCeP（舍2％P）中间合金进行物相分析,并以Al-30％Si合金为变质对象,探讨其对初晶硅的变质效果与变质机理。结果发现：A1TiCCeP中间合金组织中含有TiC、AlP、TiAl3和Ti2Al20等物相,当A1TiCCeP的添加量（以磷的实际添加量计算）为Al-30％Si合金质量的0．15％时,对初晶硅变质效果显著,平均尺寸约为281zm,优于商用Cu．P中间合金。     

Study on Grain Refining and Metamorphism of ZL111 Aluminium Alloys

Vacuum sintering and ball milling methods were employed in the preparation process of Ti-C grain refinement and the ability of refiners with varying ratios of Ti and C to refine ZL111 crystal grains was tested. The refinement effect of the Ti-C ratios on tensile strength, elongation percentage, Brinell hardness, pro-eutectoid αAl and the size of the Si phase of ZL111, after modification by rare-earth and strontium nitrate, were studied by means of metallographic examination, SEM and mechanical property tests. The results show that there is an obvious increase in the tensile strength and elongation percentage of refined ZL111 with these new Ti and C refiner compounding powders, while Brinell hardness remained more or less constant. The pro-eutectoid αAl is considerably reduced in size and the Si phase shows a finer and rounder structure. The refiner exhibits a good grain refining performance when the Ti-C ratio is 25：1, for Al crystals can favorably easily form nuclei and grow up along the TiC surface thanks to the TiAl3 generated by surplus Ti and Al. The mechanical properties have clearly been improved by the addition of strontium nitrate to ZL111. The effective factors in the modification of mechanical properties of ZL111 are in order of importance： strontium nitrate, Ti-C ratio and rare earth.     

Ti-C-Al-Fe_2O_3反应体系的热力学及形成产物的分析

针对Ti-C-Al-Fe2O3体系进行了热力学计算,并结合DSC及XRD分析,为研究该体系反应合成TiC,Al2O3提供了理论依据.计算结果表明：该体系在发生SHS反应时,可以生成TiC,Al2O3,Fe2Ti,TiAl3,Fe3C和Al4C3等产物,但TiC,Al2O3的热力学稳定性要远远大于Fe2Ti,TiAl3,Fe3C和Al4C3等相,因此,在1600℃的钢液引燃的SHS反应过程中,只能生成TiC,Al2O3两种产物.通过XRD分析也证明了在反应产物中只有TiC,Al2O3两种物质形成.     

Preparation of TiAl/Ti2AlC Composites with Ti/Al/C Powders by In-situ Hot Pressing

TiAl/Ti2AlC composites were prepared by in-situ hot pressing of TilAl/C powders mixtures and sintered at different temperatures were investigated by X- ray diffraction （ XRD ） of samples. The reaction procedure of Ti-Al-C system could be divided into three stnges. Below 900℃ , Ti reacts with Al to form TiAl intermetallics ; above 900 ℃ , C reacts with remain Ti to form TiC triggered by the exothermal reaction of Ti and Al ; TiAl reacts with TiC to produce dense TiAl/Ti2AlC compasites.In the holding stage, ternary Ti2AlC develops to layered polycrystal and composites pyknosis in the meanwhile. The mechanism of synthesis and microstructure was especially discussed.