氧含量及过热度对铸态Zr_(52.5)Cu_(17.9)Ni_(14.6)Al_(10)Ti_5大体积玻璃合金微观组织结构及力学性能的影响

利用射流成型法制备了厚度为２ｍｍ的Ｚｒ５２．５Ｃｕ１７．９Ｎｉ１４．６Ａｌ１０Ｔｉ５金属玻璃薄板,通过控制氧含量和过热度来改变 玻璃薄板中淬态结晶相的体积分数。研究表明：低的氧含量水平和高的过热度有利于提高该合金的玻璃形成能力,形 成完全非晶的合金;完全非晶的 ２ｍｍＺｒ５２．５Ｃｕ１７．９Ｎｉ１４．６Ａｌ１０Ｔｉ５大体积金属玻璃薄板其断裂应力为 １７１０ＭＰＳ,弹性模量为 ８０ＧＰａ,弹塑性为２．２％。提高合金中的氧含量水平或者降低熔体过热度都有利于结晶相析出。基体中出现２％和６％的结晶相时,断裂应力分别降为１５８ＭＰａ和１２２０ＭＰａ．淬态结晶相的析出改变了Ｚｒ５２．５Ｃｕ１７．９Ｎｉ１４．６Ａｌ１０Ｔｉ５大体积金属玻 璃剪切流变的变形方式,使材料脆断。     

Zr52.5Ni14.6Al10Cu17.9Ti5块体玻璃合金等温晶化与结构转变

对采用射流成形方法制备了Ｚｒ５２．５Ｎｉ１４．６Ａｌ１０Ｃｕ１７．９Ｔｉ５块体玻璃合金进行等温退火,利用Ｘ射线衍射和ＳＥＭ及ＴＥＭ分析了块状玻璃态合金等温晶化时相转变及组织转变。     

Zr52.5CU17.9Ni14.6Al10Ti5块体非晶退火后的力学性能

观察亲测试了Ｚｒ５２．５Ｃｕ１７．９Ｎｉ１４．６Ａｌ１０Ｔｉ５块体非晶在不同退火条件下的显微组织与力学性能,等温退火后可以得到尺寸约为３０－６０ｎｍ金属间化合物相用分布在非晶基体上的混合结构,研究表明：Ｐ块体非晶的压缩屈服强度为１．６６ＧＰａ,断裂强度为１．７８ＧＰａ,塑性约为０．５％,等温退火后,材料强度随着析出纳米相的体积分数（Ｖ）的培加发生明显的变化,Ｖ＝１８％时为１．９１ＧＰａ,Ｖ＝４７＾     

Zr50Ti5Cu18Ni17Al10块体金属玻璃的热稳定性和力学性能

采用差示扫描量热仪以连续加热的方式研究了Zr50Ti5Cu18Ni17Al10块体金属玻璃的热稳定性。其玻璃转变激活能(Eg)以及晶化激活能(Ep1和Ep2)分别为438±11,284±8和323±11kJ/mol。采用压缩试验研究了金属玻璃的室温力学性能,初始应变速率为1×10-4s-1。直径为3mm的金属玻璃棒呈现良好的力学性能,最大塑性应变达3%,杨氏模量和断裂强度的最大值分别为90GPa和1968MPa。多条剪切带的交织、分叉和滑移以及宽度为60?m的较大临界剪切台阶是Zr50Ti5Cu18Ni17Al10块体金属玻璃具有较高压缩塑性的主要原因。     

La、Zr微合金化对Al-5Mg-0.2Ti合金微观组织和力学性能的影响

采用铸锭冶金法制备了含稀土La和Zr的Al-Mg-Ti合金,通过力学性能测试及金相显微镜、扫描电镜、能谱和X射线衍射仪,观察分析了La、Zr微合金化对Al-Mg-Ti合金微观组织和力学性能的影响。结果表明,添加0.2%Zr能有效细化Al-Mg-Ti合金晶粒,说明Ti、Zr的细化作用是相容的,同时基体中析出的脆硬相Al_3Zr能显著提高合金硬度,但弱化了晶粒细化对合金强度和塑性的影响。0.2%La和0.2%Zr复合添加时的细化效果更为显著,合金的平均晶粒尺寸仅为55μm,同时La的添加有效避免了脆硬相Al_3Zr的析出和粗化,使合金的强度和塑性都得到了显著的提高,而硬度变化较小。     

Zr5oTi5Cu18Ni17Al10块体金属玻璃的热稳定性和力学性能

采用差示扫描量热仪以连续加热的方式研究了Zr50Ti5Cu18Ni17Al10块体金属玻璃的热稳定性.其玻璃转变激活能(Eg)以及晶化激活能(Ep1和Ep2)分别为438±11,284±8和323+11 kJ/mol.采用压缩试验研究了金属玻璃的室温力学性能,初始应变速率为1×10-4 s-1.直径为3 mm的金属玻璃棒呈现良好的力学性能,最大塑性应变达3％,杨氏模量和断裂强度的最大值分别为90 GPa和1968MPa.多条剪切带的交织、分叉和滑移以及宽度为60 μm的较大临界剪切台阶是Zr50Ti5Cu18Ni17Al10块体金属玻璃具有较高压缩塑性的主要原因.     

表面粗糙度对Zr52.5Cu17.9Ni14.6Al10Ti5块体非晶合金塑性的影响（英文）

将Zr52.5Cu17.9Ni14.6Al10Ti5（Vit105）块体非晶合金棒用水砂纸和抛光膏打磨到不同粗糙度,研究表面粗糙度对试样压缩变形行为的影响。结果表明,随着试样表面粗糙度的降低,屈服强度并没有明显变化,但压缩塑性从2.3%提高到4.5%。在扫描电镜下观察断裂试样的侧面发现,塑性越大的试样,剪切带的密度越大。因此,对于非晶合金,要得到较大的塑性,降低表面粗糙度是必要的。     

热处理工艺对Ni42Ti4Al合金微观组织和力学性能的影响

利用扫描电子显微镜、透射电子显微镜和力学压缩试验机研究热处理工艺对Ni42Ti8Al合金微观组织和力学性能的影响。结果表明,铸态Ni42Ti8Al合金由Ni Ti基体和晶界网状共晶体组成。经高温固溶处理后,合金中的共晶相全部溶解。Ni42Ti8Al合金的屈服强度随时效处理温度的升高而先上升后下降,在700℃时达到最大值。     

Zn含量对铸态Mg-2Er合金的微观结构及力学性能影响

采用XRD和SEM等微观表征技术研究不同Zn添加量对Mg-2Er合金微观组织和力学性能的影响。结果表明：当Zn添加量为1%和2%时,合金主要相组成为W相和α-Mg;当Zn添加量为4%-10%时,合金中则有I相析出,合金相成分变为W相、I相和α-Mg;当Zn添加量增加至12%时,W相消失,合金中主要第二相则为I相和Mg4Zn7相。当Zn添加量为6%时,合金具有较好的拉伸力学性能,其抗拉强度、屈服强度和伸长率分别为224 MPa、134 MPa和10.4%。     

Fatigue behavior of Zr52.5Al10Ti5Cu17.9Ni14.6 bulk metallic glass

In the present study, fatigue tests were conducted on a zirconium-based bulk metallic glass (BMG), BMG-11 (Zr–10Al–5Ti–17.9Cu–14.6Ni, atomic percent), in air and vacuum to elucidate the possible environmental effects. In air, the fatigue endurance limit and the fatigue ratio were found to be 907 MPa and 0.53, respectively. These values are better than many conventional high-strength crystalline alloys. Unexpectedly, the fatigue lifetimes in vacuum were found to be lower than in air. Additional testing indicated that dissociation of residual water vapor to atomic hydrogen in the vacuum via a hot-tungsten-filament ionization gauge, and subsequent hydrogen embrittlement of the BMG-11, could have been a factor causing the lower fatigue lifetimes observed in vacuum.     

Microstructure studies of Zr65Cu17.5Al7.5Ni10 and Zr65Cu15Al10Ni10 glass forming alloys: Phase morphologies and undercooled melt solidification

Zr₆₅Cu_17.5Al_7.5Ni₁₀ (at.%) and Zr₆₅Cu₁₅Al₁₀Ni₁₀ (at.%) glass forming alloy microstructures have been investigated by means of optical and electron microscopies. They are composed of a fine eutectic matrix with eutectic dendrites (EDs) that have peculiar morphologies. Al and Cu concentrations, in these alloys, favour primary dendrites and determine the ED morphologies and compositions. Their locations within the microstructures suggest a two-step solidification process of the two undercooled melts. The identified crystalline phases indicate the occurrence of solid state phase transformations in agreement with the structural defects observed in the grains. The crystalline phases can be classified into Zr-rich, Cu-rich, Ni-rich and Al-rich compounds resulting from competing diffusion between Cu, Ni, and Al in the melts.     

Effect of ball-milling and shot-peening on Zr55Al10Ni5Cu30 alloys

Effect of ball-milling and shot-peening on a metallic glass Zr₅₅Al₁₀Ni₅Cu₃₀, which possesses a large supercooled liquid region, has been investigated by means of differential scanning calorimetry, x-ray diffractometry and transmission electron microscopy. Metallic glassy ribbons, powders and plates were prepared by melt-spinning, gas-atomizing and mold-clamp casting techniques, respectively. No structural changes were observed in both the ribbon and powder specimens by ball-milling for around 100 h; however, the powder specimens were crystallized by Fe contamination when they were ball-milled for 540 h. No structural evolution was also observed when the plate specimens were subjected to shot-peening, while crystallized plate specimens were easily amorphized by mild and short period shot-peening. These results imply high phase stability of the Zr₅₅Al₁₀Ni₅Cu₃₀ metallic glass against deformation.     

Micro-forming of Zr65Al10Ni10Cu15 metallic glasses under superplastic condition

Micro-formability behavior of the Zr₆₅Al₁₀Ni₁₀Cu₁₅ alloy sheet fabricated by using squeeze casting method, which exhibited Newtonian behavior in the supercooled liquid region, was examined by finite element methods and experiments. In micro-forming simulation on a single V-groove, micro-formability index increased with time and nearly completed die-filling was achieved in 100 s when deformed under a constant pressure of 52.6 MPa at 696 K. In micro-forming on the die with multiple V-grooves in array along its width, the degree of die-filling was predicted to depend on the V-groove position. The V-grooves near the center of the die exhibited the high degree filling ratio of 1 but it was only 0.1 near the free end. This trend was confirmed to agree with the experimental results. According to the simulation result, higher friction coefficient and longer loading time could improve the die-filling ability near the free end.     

FRICTION WELDING OF Zr55Al10Ni5Cu30 BULK METALLIC GLASS

采用摩擦焊对Zr₅₅Al₁₀Ni₅Cu₃₀块体金属玻璃进行了焊接, 当焊机主轴转速为4.0×10³---5.0×10³ r/min, 摩擦压力为80---100 MPa, 摩擦时间为0.2---0.4 s, 顶锻压力和保压时间分别为200 MPa和2 s时, 能够成功实施Zr₅₅Al₁₀Ni₅Cu₃₀金属玻璃的焊接. 用SEM, XRD和TEM观察分析未检测到晶化相, 焊缝处金属仍保持非晶状态. 金属玻璃的塑性在玻璃转变点T_g附近随温度变化很大, 在T_g以上具有良好的塑性变形能力, 这是实施摩擦焊焊接的重要基础.     

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%。     

Calorimetric study of non-isothermal crystallization kinetics of Zr60Cu20Al10Ni10 bulk metallic glass

The non-isothermal differential scanning calorimetric techniques were used to evaluate the thermal stability and crystallization kinetics of Zr₆₀Cu₂₀Al₁₀Ni₁₀ bulk metallic glass. Various models were used to analyze the non-isothermal DSC at the heating rates (?) ranging from 1 to 80 K/min. The Kissinger equation, Ozawa equation, Augis-Bennett equation, Lasocka equation, and Vogel-Fulcher-Tammann non-linear equation were employed to describe the relationship between the crystallization peak temperatures and the heating rates. The overall crystallization activation energies of the metallic glass were estimated using the Kissinger, Ozawa and Augis-Bennett methods, respectively. The local activation energies at various volume fraction of crystalline phases were obtained by general Ozawa's isoconversional method. The crystallization kinetics was specified by a function reflecting crystallization mechanism. It has been found that a critical heating rate exists at around 20 K/min, beyond which the shapes of the DSC curves and the various relationships are varied. The crystallization process of the metallic glass can be divided into two groups, i.e. a slow heating rates region with ? = 1-20 K/min, and a rapid heating rates region with ? = 30-80 K/min. The overall crystallization activation energy for the slow heating rates regions is much larger than that for the rapid heating rates region. The crystallization activation energy derived from the Kissinger's peak temperatures is 326.4 ± 11.3 kJ/mol for the slow heating rates region, and 202.2 ± 26.6 kJ/mol for rapid heating rates region, respectively. The crystallization mechanisms were discussed with Johnson-Mehl-Avrami (JMA) and normal grain growth (NGG) mode. The crystallization mechanisms are different for the two heating rates regions. A transition point was found at the NGG-controlled crystallization stage for the higher heating rates, while it was absent for the slower heating rates.     

Zr_(55)Cu_(30)Ni_5Al_(10)大块金属玻璃的等时和等温晶化(英文)

采用差示扫描量热仪(DSC)和X射线衍射仪(XRD)研究Zr55Cu30Ni5Al10大块金属玻璃的非等温晶化转变动力学和在过冷液相区的等温晶化动力学行为。在非等温过程中,采用不同方法(Kissinger,Flynn-Wall-Ozawa和Augis-Bennett)得到的Zr55Cu30Ni5Al10大块金属玻璃平均激活能彼此之间吻合很好。此外,采用Johnson-Mehl-Avrami(JMA)模型描述Zr55Cu30Ni5Al10大块金属玻璃的等温转变动力学。研究结果表明:Zr55Cu30Ni5Al10大块金属玻璃的Avrami指数n介于2.2和2.9之间,表明其晶化机制主要是扩散控制过程。在等温晶化的过程中,晶核长大主要是三维的长程有序扩散控制的过程,平均激活能为469kJ/mol。