淬火态TC4合金热循环硬化行为及断口特征

在７７－６２３Ｋ对淬火态ＴＣ４合金进行了热循环试验，测定了合金热循环后的硬度，并与６２３Ｋ时效合金的硬度进行了对比；还观察了拉伸试样断口形貌。结果表明：热应力能加速亚稳相的分解，使合金中的位错密度升高，层错和形变孪晶的数量增多；循环温度场作用下淬火态合金拉伸试样断口由韧窝型断裂向韧窝和撕裂棱混合型断裂转变。     

Simultaneous Internal Oxidation and Nitridation of Ni–Cr–Al Alloys

A series of Ni–Cr–Al alloys was subjected to thermal cycling to 1100°C in air for up to 260 1-hr cycles. All alloys exhibited poor corrosion resistance. Repeated scale spallation led to subsurface alloy depletion in aluminum and, to a lesser extent, chromium. This caused transformation of the prior alloy three-phase structures (-Cr+-NiAl+-Ni) to single-phase -nickel solution. Destruction of the external scale allowed gas access to this metal, which was able to dissolve both oxygen and nitrogen. Inward diffusion of the two oxidants led to development of a complex internal-precipitation zone: Al₂O₃ and Cr₂O₃ beneath the surface, followed by Al₂O₃, then AlN, then AlN+Cr₂N, and, finally, AlN alone in the deepest region. This distribution is shown to reflect the relative stabilities of the precipitates and the higher permeability of nitrogen. Diffusion-controlled kinetics were in effect initially, but mechanical damage to the internal-precipitation zone led to more rapid gas access and approximately linear kinetics in the long term.     

机床热变形产生的原因及常用控制方法

机床热变形是机械制造业中常见的一种不正常现象，会降低零件的加工精度。减少机床热变形的方法为：进行热误差建模和补偿，温度控制，热态特性优化设计。     

Microstructural features and properties of plasma sprayed YPSZ/NiCrAlY thermal barrier coating (TBC)

0　IntroductionThermalbarriercoatings(TBCs)arewidelyusedontheturbinebladesforaircraftpropulsionorpowergenerationtoreducethemetallicsubstratetemperature,whichleadstoincreasingengineefficiencyandloweringpollutantemissionsresultingfromallowableincreaseofoperationtemperature[1,2].Today,TBCsareattractingmoreattentionandhavewiderpotentialapplicationstoprotecthightemperaturecomponents.However,thermalbarriercoatingshaveatendencytocrackandspallinserviceduetothermalshockandthermalcyclingbetweenambient…     

Modeling of waterjet guided laser grooving of silicon

Waterjet guided laser processing is an internationally patented technique based on guiding a laser inside a thin, high-speed waterjet. The process combines the advantages of laser processing with those of waterjet cutting and offers promise as a method for processing thin and heat sensitive materials with a high degree of precision. An improved understanding of the complex interaction between laser, waterjet, and workpiece is required to enable the process to achieve its potential. A model for waterjet guided laser grooving of silicon is presented that treats the energy input of the laser, the cooling effect of the waterjet, and the melting and removal of the silicon. The thermal process is represented in detail in the new method. The model is validated by comparisons of simulation and experimental results, and the simulation provides insight regarding the details of the interactions among laser, waterjet, and workpiece.     

Cu、Nb对多元Fe基非晶合金的形成及热稳定性的影响

以具有宽过冷液相区成分的Fe-Al-Ga-P-B-（C）-Si合金作为研究对象，研究了Cu、Nb元素及其加入量对合金非晶形成能力和热稳定性的影响。结果表明，当Cu加入量超过2％（原子百分比）时，合金中有晶化相析出，而低于2％时则表现为完全的非晶态。与不加铜的非晶合金相比，含铜非晶态合金的玻璃转变温度瓦和晶化温度瓦均向高温区移动，过冷液相区△Tx减小，表明非晶合金的热稳定性下降。在非晶合金形成方面．Nb也有类似的效果。含铌0、5％合金的过冷液相区△Tx大于不含铌元素的合金，表明具有较大的玻璃形成能力和稳定性。     

WC颗粒增强Ni基合金涂层的组织与性能

利用氧-乙炔火焰喷涂＋激光重熔的方法，在低碳钢表面制备Ni60＋20％（wt）WC合金涂层。利用扫描电镜（SEM）和X射线衍射仪（XRD）对涂层进行了组织和相结构分析，测试了涂层的显微硬度、耐磨性能及抗热疲劳性能，并用钨极惰性气体保护焊对涂层作了焊接性试验。结果表明，经过激光重熔的涂层组织为γ-Ni基体上分布着Ni3B、CrB、Cr23C6等硬质相，它们和未熔的WC颗粒构成了丰富的耐磨相，增强的Ni基合金涂层，显示了良好的耐磨性和抗热疲劳性，并可进行焊接。     

THERMAL STABILITY OF THE MECHANICALLY ALLOYED Al－10Ti NANOCRYSTALLINE ALLOY DURING CONSOLIDATION PROCESS

ＴＨＥＲＭＡＬＳＴＡＢＩＬＩＴＹＯＦＴＨＥＭＥＣＨＡＮＩＣＡＬＬＹＡＬＬＯＹＥＤＡｌ－１０ＴｉＮＡＮＯＣＲＹＳＴＡＬＬＩＮＥＡＬＬＯＹＤＵＲＩＮＧＣＯＮＳＯＬＩＤＡＴＩＯＮＰＲＯＣＥＳＳＬｉａｎｇＧｕｏｘｉａｎ；ＬｉＺｈｉｃｈａｏ；ＷａｎｇＥｒｄｅ（...     

Effect of adding methods of metallic phase on microstructure and thermal shock resistance of Ni/（90NiFe2O4-10NiO） cermets

Ball mixing and electroless plating were respectively used as the adding methods of metallic phase to prepare Ni/（90NiFe2O4-10NiO） cermets for the inert anode in aluminum electrolysis. The microstructure and thermal shock resistance of cermet samples were studied. The results show that, for the samples prepared by ball mixing method, aggregation of metallic phase is found in either the green blocks or sintered samples and the extent of aggregation increases with the increase of metal content. For 6.5Ni/（90NiFe2O4-10NiO） cermets prepared with electroless plating method, the homogeneous and fine metallic particles are found in either the green compacts or sintered samples, but the relative density and thermal shock residual strength decrease by 3% and 28%-58% respectively, compared with samples prepared with ball mixing method.