热喷涂制备Fe基非晶涂层的磨损行为研究进展

Fe基非晶合金具有高强度、高硬度、优异的耐磨损性、成本低等优点,但室温本征脆性和有限的玻璃形成能力极大地限制了其作为工程材料的应用前景.利用热喷涂技术制备出的Fe基非晶涂层在保留优异性能的同时,又可以实现其在大尺寸工件的表面防护应用.对Fe基非晶涂层的制备方法,以及非晶涂层的内部组织结构和外部服役环境对Fe基非晶涂层的...     

锆基非晶合金在NaOH溶液中的腐蚀行为

用电化学极化曲线研究锆基非晶合金Zr53.5Cu26.5Ni5Al12Ag3在25℃和60℃温度下,在0.01 mol/L和0.1 mol/L的NaOH溶液中腐蚀100 h的腐蚀行为,并用金相显微镜和扫描电镜对腐蚀前后试样的表面形貌进行观察与分析.极化曲线的测试结果表明：锆基非晶合金在25℃下,在浓度为0.01 mol/L和0.1 mol/L的NaOH溶液中浸泡100 h,随着NaOH溶液浓度的升高,非晶合金的耐腐蚀能力下降;锆基非晶合金在25℃和60℃下,在浓度为0.01 mol/L的NaOH溶液中浸泡100 h,随着NaOH溶液温度的升高,非晶合金的耐腐蚀能力下降;锆基非晶合金和晶态合金在60℃下,在浓度为0.1 mol/L的NaOH溶液中浸泡100 h,非晶合金的耐腐蚀性能优于晶态合金.最后根据电化学腐蚀原理,从腐蚀介质温度和浓度方面的性质探讨锆基合金耐蚀性能的因素.     

原子尺寸因素对块体非晶形成能力的影响

块体非晶的研究无论在理论上还是在应用上都有重要意义,而非晶形成能力是决定非晶制备的关键因素之一.通过研究原子尺寸分布对非晶形成能力的影响,计算了原子尺寸差函数与合金非晶形成能力间的关系,系统地分析了其机理,并对其合理性进行了验证.结果表明,原子尺寸差函数可以估计合金体系的非晶形成能力.相同合金体系中,非晶形成能力与基元素的原子百分含量存在线性关系.     

铝基非晶合金的玻璃形成能力、热稳定性以及应用展望

Al基非晶合金良好的综合性能表现,使其正在成为新一代工程材料,得到了人们的广泛关注和应用研究,但获得大尺寸的非晶材料成为其得到工业应用的一项难题。本文对铝基非晶合金的发展历史、综合性能、玻璃形成能力及其热稳定性进行了介绍,并对大块铝基非晶合金的探索及应用进行了展望。     

Fe基、Ni基合金原子键强度的表征

本文用化学键参数来表征Fe基、Ni基合金原子键强度f_1,并用f_1和键参数图解释合金元素对Fe基、Ni基合金强化的影响规律。     

不同磁芯材料对电流探头传输阻抗Zt的影响

通过对铁基、钴基非晶合金与铁氧体软磁材料的性能和实际实验结果的分析、比较，由于非晶合金自身良好的磁性能，将其用于电磁兼容性试验设备中作为低频干扰电流探头的磁芯材料，实验证明选用铁基、钴基非晶合金，可使电流探头的检测灵敏度、精确度大大提高，从而为扩大非晶合金这一功能性材料的应用范围提供了实验依据．     

内应力假说和脆性材料特性参数的尺寸效应(Ⅲ)

内应力假说建立了一组描述脆性材料强度指标和弹模指标尺寸效应的方程 ;该假说认为内应力场或者说内应力能会随试件尺寸加大而加大 ,在引起材料强度指标随试件尺寸加大而减小的同时 ,还会引起材料初始切线弹模随试件尺寸加大而加大的弹模尺寸效应 .文中利用尺寸效应的方程对 3组不同尺寸的混凝土试件强度和弹模试验数据以及多组不同冰晶粒径的多晶冰试件强度和弹模试验数据进行了计算 ,结果表明理论公式在描述材料强度尺寸效应 (或粒径效应 )和弹模指标尺寸效应时具有良好的精度 ,证明了内应力理论是正确的 .对内应力理论在解释脆性材料破坏形态、尺寸效应等多种力学特性方面的应用进行了总结 .     

Fe对Zr55Al10Ni5Cu30非晶形成能力及力学性能的影响

为了进一步提高锆基大块非晶合金的玻璃形成能力及力学性能,采用铜模吹铸法制备了（Zr0.55Al10Ni0.05Cu0.30）100-xFex（X=1,5,10）系列合金,通过X射线衍射（XRD）、差示扫描量热法（DSC）以及压缩实验和SEM进行材料分析。研究表明：微量Fe有助于改善非晶合金在压缩变形时剪切带内的应力分布,提高材料的综合性能,当Fe添加量为1％时,塑性应变εp达到5．9％,强度达到1．89GPa,同时,随着Fe添加量的增加,过冷温度区间ΔTx减小,热稳定性减小,非晶形成能力降低。     

类金刚石薄膜膜基结合强度优化技术研究进展

类金刚石膜是由sp2键合的石墨与sp3键合的金刚石组成的一类碳膜,具备石墨的润滑特性和金刚石的高硬度,在降低摩擦因数、耐磨等方面具有重要应用价值.但薄膜较大的残余应力以及膜基结合问题的存在,限制了其在机械、电子、医学等范围内的普遍应用.国内外研究表明,掺杂元素、生成过渡层、设计多层膜成为有效改善类金刚石薄膜膜基结合强度...     

大块锆基非晶合金Zr53．5Cu26．5Ni5Al12Ag3的盐雾腐蚀行为

采用铜模吸铸法制备直径为5 mm的Zr53.5Cu26.5Ni5Al12Ag3,用电化学极化曲线方法考察该大块锆基非晶合金及相应的晶态合金在55℃中性盐雾气氛下腐蚀120 h的腐蚀行为,并用金相显微镜、SEM和EDS对腐蚀前后试样的表面形貌和成分进行观察与分析.极化曲线测试结果表明,在55℃中性盐雾气氛下,大块锆基非晶合金比相同成分的晶态合金具有更好的耐盐雾腐蚀性能,腐蚀120 h后,Icorr=9.922×10-7A/cm2,比同条件下的晶态合金小3个数量级.SEM分析表明非晶合金表面没有发生明显的腐蚀,表面保持光洁.EDS分析表明非晶合金腐蚀产物为Al的氧化物,相应的晶态合金表面腐蚀产物为Al和Ni的氧化物.     

Testing of High-Strength Zr-Based Bulk Metallic Glass with the Split Hopkinson Pressure Bar

The split Hopkinson pressure bar(SHPB) was used to determine the dynamic compressive strength of the high-strength Zr38Ti17Cu10.5Co12Be22.5 bulk metallic glass at strain rate on the order of 102 s-1.It is shown that at high strain rates beyond about 1 000 s-1,uniform deformation within the metallic glass specimen could not be achieved and dispersion in the transmitted pulse can lead to discrepancies in measuring the dynamic failure strength of the present Zr-based bulk metallic glass.Based on these reasons,a copper insert was placed between the strike bar and the input bar to obtain reliable and consistent experimental data for testing of the Zr38Ti17Cu10.5Co12Be22.5 bulk metallic glass using the SHPB.Negative strain rate sensitivity was found in the present Zr-based bulk metallic glass.     

Effects of small amount Ta on the characteristics ofthe Zr-Al-Ni-Cu-Ta bulk metallic glass

The effects of Ta on the characteristics of the Zr-base BMG (bulk metallic glass) were investigated. Zr55Al10Ni5Cu30-xTax(x=1,2,4) bulk metallic glasses (BMGs) with 3.5 mm diameter and 70 mm length were successfully prepared by using combined jet and copper mold casting. A small amount of Ta addition does not change the glass transition temperature, crystallization temperature, and supercooled liquid region obviously, but Ta promotes composition separation and two-stage crystallization. The stable crystalline phases include ZrENi, CuZr2, AlEZr3 intermetallic compounds and Ta-rich solid solution after annealing the Zr-Al-Ni-Cu-Ta alloys at 753 K. Zr55Al10Ni5Cu30-xTax (x=1,2,4) bulk glassy alloys exhibit a better compressive strength. The stress-strain curve shows a zigzag feature, and the fracture surface shows intersecting of shear bands. It may correlate with the inhomogeneous feature of amorphous structure.     

添加微量稀土钇对铜基合金非晶形成能力的影响

针对铜基非晶合金玻璃形成能力问题,分析了添加微量稀土元素Y对合金的玻璃形成能力、热稳定性的影响,利用铜模吸铸法制备出Cu-Zr-Al-Y9mm非晶合金.研究结果表明：制备的9mm铜基非晶合金试样（Cu45Zr47Al8）97Y3,在过冷液相区ΔT和约化玻璃转变温度Trg分别是79.42K和0.775 3.随着稀土元素Y含量的增加Trg值变小,合金的非晶形成能力降低,通过Trg值变化可以判别该合金的非晶形成能力.     

Zr63Al10Ni10Cu14Nb3大块非晶合金的力学行为研究

通过电弧熔炼并利用吸铸的方法制备了长70 mm、直径3 mm的Zr63Al10Ni10Cu14Nb3大块非晶合金.热稳定性分析表明:该合金具有较大的过冷液相区.室温压缩实验显示合金具有很高的屈服强度,在合金发生屈服之后应力-应变曲线上有明显的锯齿现象和一个明显的应变软化阶段.结合断口形貌特征,分析并讨论了非晶合金的剪切断裂机理.     

Chemical short-range order domain in bulk amorphous alloy and the prediction of glass forming ability

Since the discovery of bulk Zr-Ti-Cu-Ni-Be[1] and Pd-Ni-Cu-P[2] metallic glasses with ex-traordinary high glass forming (GFA) ability and critical cooling rate lower than 100 K/s, great attention has been paid to the structure of BMG alloys. Experimental results of X-ray and neutron diffraction or scattering have provided ample evidence that there is a short-range order in BMG alloys. Metallic glasses always exhibit strong compound forming tendency and the corresponding anomalies of t…     

Glass formation of ternary Sm-based Sm-Al-Co bulk metallic glasses

Ternary Sm-based Sm-Al-Co alloys at specific compositions designed using an e/a- and cluster-related criteria exhibit high glass forming abilities and form bulk glassy rods of 3 mm in diameter by a copper mold suction-casting method. Four composi- tions of bulk metallic glasses (BMGs) are Sm50Al25Co25, Sm52Al24Co24, Sm54Al23Co23 and Sm56Al22Co22, which all satisfy a constant conduction electron concentration of 1.5. Among them, the BMG exhibiting the largest reduced glass transition temperature (Trg) is Sm50Al25Co25, which reaches 0.648. The glass transition temperature Tg and the onset crystallization temperature Tx of this alloy are respectively 579 and 640 K at a heating rate of 20 K/min.     

Strain rate response of a Zr-based composite fabricated by Bridgman solidification

Zr_(58.5)Ti_(14.3)Nb_(5.2)Cu_(6.1)Ni_(4.9)Be_(11.0) bulk metallic glass matrix composites,containingβ-Zr dendrites,were fabricated by Bridgman solidification at the withdrawal velocity of 1.0 mm/s through a temperature gradient of～45 K/mm.Subjected to the increasing compressive strain rates,the monotonic increasing and decreasing were obtained for the maximum strength and the fracture strain,respectively.The results show that high strain rate may induce the insufficient time for the interaction between s...     

Compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni bulk metallic glasses

Starting from the quaternary Cu47Ti34Zr11Ni8 alloy, the compositional dependence of thermal and elastic properties of Cu-Ti-Zr-Ni alloys was systematically investigated. Quaternary Cu-Ti-Zr-Ni alloys can be cast directly from the melt into copper molds to form fully amorphous strips or rods with the thickness of 3-6 mm. The evidence of the amorphous nature of the cast rods was provided by X-ray spectra. The measured glass transition temperature (Tg) and crystallization temperature (Tx) were obtained for the alloys using differential scanning calorimetry (DSC) at the heating rate of 20 K/s. In the results, the differences between the glass temperature and the crystallization tempera-ture (△Tx=Tx-Tg) are measured with values ranging up to 33-55 K. The reduced glass transition temperature (Trg), which is the ratio of the glass temperature to the liquidus temperature (T1), is often used as an indication of the glass-forming ability of metallic alloys. For the present Cu-Ti-Zr-Ni alloys, this ratio is typically in the range of 0.5838-0.5959, characteristic of metallic alloys with good glass-forming ability. The elastic constants for several selected alloys were measured using ultrasonic methods. The values of the elastic shear modulus, bulk modulus, and Poisson's ratio were also given.     

Nd_(60)Al_(10)Ni_(10)Cu_(20)大块金属非晶的玻璃转变和晶化特性研究

用铜模吸铸法制得了一种直径为5 mm、成分为Nd60Al10Ni10Cu20的大块非晶合金.与富Fe类Nd基非晶不同的是,这种新型的Nd基大块非晶具有明显的玻璃转变过程和稳定的过冷液相区.磁性测试表明,在室温下表现为顺磁性.热分析实验发现,随着升温速率的增大,样品的过冷液相区变宽,并且玻璃转变温度和晶化温度有明显的向高温方向移动的趋势.研究了该大块非晶的玻璃转变动力学和晶化动力学,并给出了Kauzmann温度Tk,Vogel-Fulchers-Tamman温度T0g以及脆性系数m等重要参数.