THERMOGRAVIMETRIC STUDY OF DIRECT CARBURIZING BY NATURAL GAS

<正> 在渗碳等金属表面化学热处理过程中,金属的渗碳、脱碳、氧化、还原等均出现高温下重量变化,根据热天平的工作原理,可以对金属表面渗碳过程进行工艺研究和机理探讨。 我国的天然气资源丰富,直接用天然气作碳源在金属表面渗碳,似有值得推广采用的意义。 曾以20CrNiMo钢用热重法研究常压渗碳和真空渗碳两种工艺,大量实验结果说明:用热重法研究气体渗碳的工艺参数,并直接采用天然气渗碳,都是可行的。     

PHYSICAL CHEMISTRY OF DEOXIDATION OF STEEL

在本文中,作者首先讨论了Fe-O溶液与H_2O-H_2混合气体间的平衡的较新的实验数据,接着讨论了Fe-C-O系统的平衡。然后重点地分别讨论了铝、硅、锰的脱氧反应平衡与脱氧反应产物的组成.其次较简单地讨论了铬、钒、钛、硼、锆、磷、铌、钽以及某些复合脱氧剂的脱氧能力.最后用脱氧曲线将各元素的脱氧能力作一比较。     

Ⅰ型载荷下缺口前端氢浓度分布的研究

采用离子探针微分析仪,对Ⅰ型载荷下21Cr9Ni9MnN奥氏体钢缺口前端氢浓度分布进行了研究。结果表明,缺口前端存在两个氢浓度的富集峰,一个位于缺口顶端,另一个距缺口稍远。缺口顶端的氢富集峰是位错对氢陷阱作用结果,而静水应力导致远离缺口的氢富集峰。对缺口前端氢的富集过程以及应力强度因子对氢浓度分布的影响进行了讨论。     

Cu对Al-Li合金组织结构与性能的影响SCIEI

本文研究了3种Cu/Li比的Al-Li-Cu-Zr合金的时效析出组织及其性能。结果表明,实验合金时效由两级硬化过程所组成,其中第一级硬化是δ′相(3号合金为δ′+T_1相)强化而引起;第二级硬化是由于δ′+T_1(3号合金为δ′+T_1+θ′)的复合强化作用。当T_1相板条与δ′相颗粒相遇时,δ′相逐渐被T_1相吞并。Cu/Li比增加,合金的强(硬)度上升,但塑性下降,拉伸断口由穿晶变为沿晶形式,这与高Cu/Li比合金中晶界析出平衡相有关。     

Ti和V对Fe中氢与位错交互作用的影响

研究了Fe-0.5wt-%Ti和Fe-0.5wt-%V合金中由氢与位错交互作用所形成的氢致冷加工内耗峰(H-CWP)。实验结果表明:合金元素对H-CWP、对氢与位错之间的交互作用有显著的影响,与氢作用愈强的元素,对H-CWP的影响愈大,内耗实验结果与力学性能之间存在着一定的联系.     

EFFECT OF INITIAL CRYSTALLIZATION ON MAGNETIZATION OF METALLIC GLASSES(Fe_(1-x)Co_x)_(78)Si_(10)B_(12)

<正> 文献[1]曾对金属玻璃(Fe_(1-x)Co_x),_(78)Si_(10)B_(12)的晶化,作过X射线衍射和透射电镜研究,指出初期晶化相为相应晶态Fe_(1-x)Co_x的室温平衡相.本工作将在验证这一结论的基础上,研究初期晶化对一定磁场强度下磁化强度(定场磁化)的影响。 一、样品和实验方法 成分为(Fe_(1-x)Co_x)_(78)Si_(10)B_(12)(x=0.1,0.5,0.7,1)的合金用单辊快淬法制成截面为～1×0.3mm的金属玻璃窄带,用示差扫描热分析法测定其晶化温度T_(cr)(升温速率10℃/min)分别为505,490,440和420℃.磁性试样在石英管式炉中依次进行退火,退火温度T_a=350-500℃,除了x=0.7的样品在T_a≥450℃退火10min外,T_a≤450℃退火20min,     

Ion Flotation of Scandium

Scandium was recovered from dilute chloride solutions with potassium salt of saturated C_8～C_(12)fattyacids as surfactant by Ion flotation.The optimum comprehensive results of physical properties,stability andscandium concentration of the foam formed with potassium caprate CH_3(CH_2)_8 COOK can be obtained.Re-covery of scandium in the foam was 98% at pH 3.8～5.0 and 25～55℃.The experimental results of 0.3 L/minairflow rate was satisfactory for flotation column.It is of a great potential for using ion flotation technique toconcentrate scandium from dilute solutions.     

MODEL OF CLEAVAGE CRACK PROPAGATION ACROSS BOUNDARY

In the light of analysis of the features of cleavage fractographs of low carbon steel,the stresscriterion for cleavage crack propagation across ferrite grain boundary was established on thesupposition that resistance to the propagation results from an arbitrary mutual orientation ofthe cleavage plans in the neighbouring grains.On the basis of concept of statistical distribu-tion of cleavage plane in space,the probabilistic characteristic of cleavage process was ex-pounded,and the fracture stress of the cracked specimen over temperature range in whichfracture is initiated by cleavage mechanism was calculated by means of finite element analysisprogram and the calculated result was found to be in agreement with that measured.     

SiC涂层碳纤维增强铝复合丝的机械性能及其界面特性

研究了不同热处理温度对碳化硅涂层碳纤维增强铝复合丝的拉伸强度影响,结果表明:500℃热处理2h及550℃热处理1h后使复合丝的拉伸强度提高,600℃以上的热处理都使复合丝的拉伸强度下降,通过测量从复合丝中分离出来的纤维强度,表明碳化硅涂层对碳纤维具有良好的保护作用,用电子探针及能量损失谱分析了C/Al界面的稳定性。     

Temperature Dependence of the Magnetocrystalline Anisotropy in Nd_2Co_(14)B Compound

Easy and hard magnetization curves of Nd_2Co_(14)B compound have been measured withextracting-sample-magnetometer(μ_0H_(max)=6T)at 10～300 K.Magnetic anisotropy constants K_1 and K_2have been determined by fitting the hard magnetization curves,in which only K_1 ,K_2 and misalignment anglehave been taken as fitting parameters.The values of K_1 and K_2 at 4.2 K were derived by extrapolation.Anisotropy coefficients,x_2~° and x_4~°were derived from the anisotropy constants.The anisotropy constant K_2increases rapidly with increasing temperature when TT_(sr).The temperature depen-dence of the magnetic anisotropy coefficient x_2~° was fitted with the formula.The anisotropy coefficients x_2~°can be well described by the tenth-power law from 4.2 K to T_(sr)and by the sixth-power law from T_(sr_ to 300 K.