Mg65Cu25Y10金属玻璃时效处理的研究

采用铜辊旋淬法制备Mg65Cu25Y10金属玻璃条带,并在玻璃化温度附近对其进行时效处理.结果表明,对应不同的时效处理温度与时间,该合金条带具有不同的相组成.同时,时效处理对其室温塑性也有很大的影响,时效处理后条带的塑性变差.通过对时效处理前后条带的X射线衍射图谱和扫描电镜照片的分析,对Mg65Cu25Y10金属玻璃的晶化机理进行了初步探讨.     

Zr53.7Ni9.4Cu28.5AI8.4块体金属玻璃的激光焊接

采用激光焊接技术对Zr53.7Ni9.4Cu28.5Al8.4块体金属玻璃进行焊接试验,研究在激光焊接下不同工艺参量对焊接接头组织的影响,探讨了焊接热循环过程中焊缝和热影响区的晶化行为。结果表明,固定激光功率1 200 W,焊接速度从8 m/min提高到30 m/min,均成功获得了无气孔和裂纹等缺陷的焊接接头。焊缝熔化区保持了非晶结构,热影响区则出现不连续的呈弧形分布的点状晶粒。随着焊接速度的提高,热影响区的晶粒尺寸逐渐减小。     

Zr60Al10Cu30合金的玻璃形成能力和力学性能

利用铜模吸铸法制备了直径分别为3、4和6 mm的阶梯型Zr60Al10Cu30棒状试样,采用X射线衍射、扫描电镜和万能试验机等研究了所制备合金的玻璃形成能力(GFA)和力学性能。结果表明,Zr60Al10Cu30合金的非晶临界尺寸接近6 mm,具有较强的玻璃形成能力。其中全非晶结构的Ф4 mm合金块体金属玻璃的抗压强度、塑性应变分别为1 595 MPa和1.95%,断口呈现非晶典型的脉状纹络和脆性平滑区。在Ф6 mm处的原位生成晶体/非晶基复合材料中,新析出DO3结构的AlCu2Zr晶体相和Cu10Zr7共晶正交晶体相,增加了合金的脆性,最终断裂行为取决于塑性相和脆性相之间的竞争,致使其抗压强度和塑性应变分别为1 345 MPa和0.5%。     

回火温度对含Nb低合金高强度钢氢行为的影响

采用X射线衍射、电化学氢渗透和动态充氢拉伸试验研究了含Nb低合金高强度钢560、600和640℃回火的氢行为,建立了氢扩散系数、氢浓度、氢扩散激活能与氢陷阱密度之间的定量关系。结果表明,随着回火温度的升高,试验钢的位错密度降低,氢陷阱密度降低,氢扩散系数增大,氢扩散激活能和氢浓度降低,氢脆敏感性下降。     

Pd20Pt20Cu20Ni20P20 高熵金属玻璃的热稳定性和热塑成形性

采用差示扫描量热法、X射线衍射和热力学分析研究了Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀高熵金属玻璃（HEMG）的热稳定性和热力学性能。结果表明,与其他经典贵金属基金属玻璃相比,Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ HEMG具有相当的性能和鲜明的特点。     

Cu56Hf27Ti17块体金属玻璃的缺口韧性

通过研究Cu-Hf-Ti三元合金的玻璃形成能力对合金成分的依赖性,优化出Cu₅₆Hf₂₇Ti₁₇和Cu₅₇Hf₂₇Ti₁₆合金,其形成金属玻璃棒材的临界直径为5 mm.采用单边缺口试样测量的Cu₂₆Hf₂₇Ti₁₇金属玻璃的缺口韧性KQ为（92±10）MPa·m^1/2,几乎是Cu₄₉Hf₄₂Al₉金属玻璃(K_Q=（56±9）MPa·m^1/2)的一倍,是目前所知韧性最高的铜基块体金属玻璃.相对于Cu₄₉Hf₄₂Al₉金属玻璃,Cu₅₆Hf₂₇Ti₁₇金属玻璃的高韧性与其高Poisson比（v=0.361）和低剪切模量（G=38.6 GPa）关联.Cu₅₆Hf₂₇Ti₁₇块体金属玻璃的高韧性表现为裂纹尖端形成大塑性区,在裂纹萌生与扩展过程中,形成大尺寸剪切滑移区和脉纹花样区.Cu₅₆Hf₂₇Ti₁₇和Cu₄₉Hf₄₂Al₉块体金属玻璃在缺口韧性上的差异表明,从Cu-Zr/Hf基合金中去除Al元素有利于金属玻璃的韧化.     

内生型(Ti0.474Zr0.34Cu0.06Be0.126)100 - x Fe x (x=0, 2)金属玻璃基复合材料的动态力学行为

为了解内生β-Ti相的Zr/Ti基金属玻璃复合材料的动态力学性能和热力学稳定性,采用力学弛豫谱研究了(Ti_0.474Zr_0.34- Cu_0.06Be_0.126)_100-xFe_x（x=0,2）金属玻璃复合材料。通过引入Fe元素,提高了β-Ti相的稳定性。此外,还发现了一个异常的内耗峰,这是由于在亚稳的β-Ti相中析出ω-Ti所引起的。在玻璃化转变温度T_g以下,由于相变和非晶基体部分结晶的耦合效应,2种金属玻璃复合材料的储能模量均表现出异常过冲行为。所得结果为更好地理解内生亚稳β-Ti型金属玻璃复合材料的复杂动态力学弛豫行为提供了借鉴。     

球磨对Zr-Cu-Al-Ni金属玻璃粉末结构与吸放氢性能的影响

本文研究了球磨对气雾化法所制备的Zr50.7Cu28Al12.3Ni9金属玻璃粉末结构与吸放氢性能的影响。气雾化的金属玻璃粉末在经过80 h的球磨后,仍呈现为非晶态。球磨对金属玻璃粉末吸放氢性能的影响在一台全自动Sieverts装置上进行了测量。球磨之后,金属玻璃粉末的吸氢性能获得提升,粉末的饱和吸氢量从雾化态的0.96 wt.% (H/M≈0.7)提升至了球磨后的2.66 wt.% (H/M≈1.9)。然而,由于吸氢后金属玻璃粉末内部生成稳定的氢化物相,使得球磨后的金属玻璃粉末的放氢性能未能获得提升。     

奥氏体不锈钢焊缝金属的氢致马氏体相变

用X射线衍射的方法 ,研究了充氢以及随后的时效过程中氢致奥氏体不锈钢焊缝金属 (30 8L和 347L)的马氏体相变和晶体结构的变化规律。结果表明 ,充氢能造成奥氏体点阵的膨胀和畸变。氢引起的奥氏体不锈钢焊缝金属的晶格畸变分别为 2 .7%(30 8L)和 2 .9% (347L) ,明显大于奥氏体不锈钢基体所产生的晶格畸变 1.2 % (30 4L)。充氢过程中 ,奥氏体不锈钢焊缝金属能发生ε马氏体相变。并且在随后的时效过程中 ,一部分ε马氏体转变为α′马氏体。即相变的顺序是γ→ε→α′。充氢后以及随后的时效过程中ε α′马氏体的总量大体保持不变 ,时效 2 4h后 ,ε和α′马氏体的相对含量达到稳定 ,并且长时间时效也不消失     

Mg61Cu28Gd11和(Mg0.61Cu0.28Gd0.11)99.5Sb0.5非晶合金的晶化动力学和腐蚀行为（英文）

研究0.5%(摩尔分数)Sb的引入对Mg61Cu28Gd11块体非晶合金性能的影响。利用差热扫描量热仪测试样品的晶化动力学。结果表明:在等时加热的过程中,非晶合金的玻璃转变温度、起始晶化和峰值晶化温度都表现出对加热速率强的依赖性。基于Oawza方法可以确定非晶合金的起始晶化和峰值晶化激活能。Vogel-Fulcher-Tamman公式分析表明:含Sb元素的非晶合金具有更高的强度系数和更长的延迟时间。采用电化学极化和失重测试方法研究2种玻璃合金的腐蚀行为。与基体非晶合金相比,添加微量Sb降低了非晶合金的在含Cl-的碱性溶液中的钝化电流密度和腐蚀速率,表现出相比基体合金更为优越的耐蚀性。最后基于"点缺陷模型"进一步分析微量Sb元素对基体合金耐蚀性能的影响机理。     

Thermodynamic properties of the Pd77.5Cu6Si16.5 undercooled liquid

Proper understanding of glass formation implies the knowledge of the thermodynamics of the undercooled melts. Specifically, high values of the excess specific heat of the liquid are expected for good glass-formers. Extending the work of Gillessen and Herlach [F. Gillessen, D.M. Herlach, J. Non-Cryst. Solids 117–118 (1990) 555–558], we re-propose a calculation of the temperature dependence of entropy difference between amorphous-liquid and crystal states.An amorphous Pd_77.5Cu₆Si_16.5 alloy has been produced by injection casting in a cylindrical copper mould. DSC measurements in the liquid, amorphous and crystalline states were performed with samples sliced from the cylinder to determine the heat of fusion, of crystallization and the difference in specific heat capacity between amorphous-liquid and crystal phases. These thermodynamic quantities are used to calculate the thermodynamic functions of the liquid-glass with reference to the equilibrium crystal mixture. The data are compared to those of other bulk glass-formers in terms of fragility plots.     

Thermal behaviour of Pd40Cu30Ni10P20 bulk metallic glass

The thermal behaviour of differently milled Pd₄₀Cu₃₀Ni₁₀P₂₀ bulk metallic glass through the glass transition has been investigated by in situ high-energy synchrotron X-ray diffraction. Repeated heating and cooling were performed between the glassy and the supercooled liquid state. The changes in positions and intensities of the first and second diffraction maxima of the as-milled powder indicate irreversible changes during first heating up to the glass transition temperature T_g due to structural relaxation. After annealing, reversible structural changes with temperature are observed upon heating and cooling in the glassy phase, and in the supercooled liquid state respectively. The shift in the position of the first maximum scales approximately with the linear thermal expansion for the glassy state; however, this relation does not hold for the supercooled liquid. The structural transition from the glass to the supercooled liquid at the glass transition temperature is reflected by the intensity of the diffraction maxima and by a reversed temperature dependence of the position of the second diffuse maximum below and above T_g. The changes of the glass structure for the decrease of free volume by annealing are found to be different from those observed for the reversible volume expansion or shrinkage by varying the temperature. Therefore, the shift of the first diffuse maximum position of bulk metallic glasses cannot be used as a measure of the change in free volume.     

Mechanical properties of monolithic Zr62Al8Ni13Cu17 bulk metallic glass

We present mechanical properties of monolithic bulk metallic glass (BMG) Zr₆₂Al₈Ni₁₃Cu₁₇ under uniaxial compression and tensile tests. It is found that the Zr₆₂Al₈Ni₁₃Cu₁₇ BMG exhibits pronounced plasticity of nearly 14% without catastrophic failure upon compression. However, it is destroyed under tension in a brittle manner. High energy X-ray diffraction has been used to detect the structural change in this BMG during both conditions. No deformation-induced nanocrystallization is detected in a 55% strained sample under compression while it only appears in the fracture-affected region upon tension. No excess free volume is obviously found in the fractured samples. We suggest that monolithic BMG alloys with small differences in atomic affinity and atomic sizes among components might have high plasticity under compression.     

Partial crystallization of as-quenched Zr55Cu30Al10Ni5 bulk metallic glass induced by oxygen

Dendritic crystals, randomly distributed into the as-quenched Zr₅₅Cu₃₀Al₁₀Ni₅ bulk metallic glass were characterized by optical microscopy, electron probe microanalysis, X-ray diffraction and electron backscattering diffraction. Oxygen enrichment is observed into these crystallites (formula: Zr₇Cu₄Al₃O, space group: Fd m, cell parameter: 5.70 Å) demonstrating the negative effect of oxygen, inducing partial crystallization during casting.     

Nanocrystallization of Pd74Si18Au8 metallic glass

The crystallization process of Pd₇₄Si₁₈Au₈ amorphous alloy has been investigated by transmission electron microscopy, small angle X-ray scattering and three-dimensional atom probe techniques. Although literature suggests that the alloy decomposes into two glassy phases prior to the crystallization, we found that the crystallization occurs directly from a single amorphous phase by the primary crystallization of fcc Pd–Au solid solution, followed by the polymorphous crystallization of the remaining amorphous phase to a Pd₃Si phase.     

添加微量Fe对Zr_(55)Al_(10)Ni_5Cu_(30)块体金属玻璃非晶形成能力和力学性能的影响(英文)

通过磁悬浮熔炼和铜模吸铸法制备直径3mm的(Zr0.55Al0.10Ni0.05Cu0.30)100-xFex(x=0,1,2,3,4)合金试样,研究Fe元素的微量添加对Zr55Al10Ni5Cu30块体金属玻璃非晶形成能力和力学性能的影响。研究表明,合理添加Fe元素(不超过3%,摩尔分数)导致约化玻璃转变温度Trg(=Tg/Tl)和参数γ(=Tx/(Tg+Tl))增大,因而其非晶形成能力增大,但添加过量的Fe元素(4%)会导致其非晶形成能力的降低。添加Fe元素也会显著地改善Zr55Al10Ni5Cu30块体金属玻璃的压缩塑性及提高其压缩断裂强度,当Fe元素的添加量为2%时,直径3mm、长度6mm的试样在压缩时出现一定的塑性及加工硬化现象。Fe元素添加量为4%形成的金属玻璃基复合材料,同样也显示良好的压缩塑性和高的压缩断裂强度。     

Zr67.8Cu24.7Al3.43Ni4.07非晶合金激光焊接晶化控制及组织性能分析

对Zr_67.8Cu_24.7Al_3.43Ni_4.07非晶合金进行激光焊接,研究激光功率和焊接速度变化对接头不同区域微观组织的影响,阐述非晶合金激光焊接接头晶化控制的工艺调控规律,并分析接头不同区域的微观结构特征与其硬度之间的关系.结果表明,采用高焊速及高能量密度的激光焊接有利于使Zr_67.8Cu_24.7Al_3.43Ni_4.07非晶合金接头的熔化区保持非晶态结构,同时伴随少量纳米晶产生.热影响区的晶化现象明显,激光功率对接头完全焊透具有较大影响,通过降低激光功率或提高焊接速度以减小热输入,热影响区的晶化程度得到有效控制.焊后接头的熔化区硬度略高于母材,而热影响区的硬度相比于母材显著降低.     

Zr41Ti14Cu12.5Ni10Be22.5非晶棒料摩擦焊接

设计了一种非晶合金摩擦焊装置,以Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5非晶棒料为研究对象,进行了摩擦焊试验.焊接样品经SEM,XRD,维氏硬度、TEM等检测,结果显示焊接界面无明显未熔合,样品仍然保持非晶态,接头硬度总体增大,接头处出现了纳米晶.采用ANSYS软件对非晶合金摩擦焊的温度场进行仿真.结果表明,在摩擦时间t=0.25s时摩擦界面中心温度超过非晶棒料玻璃转变温度,接触面全部进入过冷液相区,应进行顶锻.仿真结果与摩擦焊试验结果基本吻合,有利于指导焊接试验.     

过冷液态Zr48Cu36Ag8Al8块体非晶合金的相分离及组织演变

本文通过x射线衍射(XRD)、差示扫描量热法(DSC)和透射电子显微镜(TEM)研究了退火温度对Zr₄₈Cu₃₆Ag₈Al₈金属玻璃微观结构演化的影响。结果表明,快速凝固获得的样品为典型的非晶态结构。当样品在703K保温20分钟时,均一的非晶基体相分离成两种非晶合金,即,发生相分离。由于相分离结构与非晶基体在等温退火过程是竞争的关系,这个结构很容易向晶化态进行转变,形成AlZr₂ AlAg₃相。Zr₄₈Cu₃₆Ag₈Al₈金属玻璃的微观结构在过冷液相区等温退火过程中经历了的局部结构转变,相分离以及纳米晶转变,这个过程意味着Zr₄₈Cu₃₆Ag₈Al₈金属玻璃的微观结构对退火温度十分敏感。此外,相分离的形成可以加速纳米晶的形成。