Microstructure and thermal expansion of copper-based amorphous alloys during structural relaxation

(Cu43Zr48Al9)98Y2 amorphous alloy bar was prepared by the arc melting copper mold absorption casting method,and then,the amorphous alloy was annealed at different temperatures for different times.The influence of heating rate on thermal expansion and thermal stability was studied by thermomechanical analysis(TMA),and the microstructure evolution of the amorphous alloy during structural relaxation and crystallization was studied by XRD and TEM.Results show that the structural evolution behavior of the(Cu43Zr48Al9)98Y2 amorphous alloy can be divided into five different stages(structural relaxation preparation stage,structural relaxation stage,first crystallization stage,second crystallization stage,and grain growth stage).When the heating rate is 20 K/min,the amorphous alloy has the smallest thermal expansion coefficient and the best thermal stability.The width of the supercooled liquid region is 66.42 K.Samples with different relaxation states were prepared by annealing at the heating rate of 20 K/min.The structural evolution of amorphous alloys with different relaxation states is as follows:amorphous→CuZr2+AlCu2Zr7→CuZr2+AlCu2Zr7+CuZr(B2)+CuZr(M)+Cu10Zr7→CuZr2+AlCu2Zr7+CuZr(B2)+CuZr(M).After annealing at 706 K and 726 K(in the supercooled liquid region)for 1.5 h,the amorphous-nanocrystalline composites were obtained.When the annealing temperature is 706 K,the crystallization process of the sample is as follows:amorphous→Cu10Zr7→Cu10Zr7+CuZr,and for the sample at 726 K,it is as follows:amorphous→CuZr2+AlCu2Zr7+Cu10Zr7→Cu10Zr7+CuZr2→CuZr2+CuZr(B2)+Cu10Zr7.     

Production and mechanical properties of aluminum alloys with dispersed nanoscale quasicrystalline and amorphous particles

By the dispersion of nanoscale quasicrystalline and amorphous particles in Al phase, new Al-based alloys with good mechanical properties were developed in a high Al concentration range of 93–95 at.% for Al−Cr−Ce−Co, Al−V−Fe, Al−Ti−M and Al−Fe−Cr−Ti alloy systems. The Vickers hardness of a melt-quenched (MQ) Al_84.6Cr_15.4 alloy with almost a single icosahedral quasicrystalline phase (QC) was 710. The addition of Ce and Co in the Al−Cr binary alloys was effective for the extension of the concentration range of the QC to a lower solute concentration range. The fracture strength (σ_f) increased to 1340 MPa for the MQ Al_94.5Cr₃Ce₁Co_1.5 alloy in which the particle size and volume fraction were approximately 40 nm and 70%, respectively. The σ_f of the MQ Al₉₄V₄Fe₂ alloy was 1390 MPa and the particle size and volume fraction were about 10 nm and 50%, respectively. Similarly, σ_f of the MQ Al₉₃Ti₄Fe₃ alloy was 1320 MPa and the particle size and volume fraction were about 11 nm and 30%, respectively. Power metallurgy (P/M) Al₉₃Fe₃Cr₂Fe₂ alloy with dispersed nanoscale QC exhibited ultimate tensile strength (σ_UTS) of 660 MPa, 0.2 % proof stress (σ_0.2) of 550 MPa, plastic elongation (ε_P) of 4.5%, Young's modulus (E) of 85 GPa, Vickers hardness (Hv) of 192 and specific strength (σ_UTS/ρ) of 2.20×10⁵ Nm/kg at room temperature and σ_UTS of 350 MPa, σ_0.2 of 330 MPa and ε_P of 1.5% at 573 K. The QC structure in the P/M Al₉₃Fe₃Cr₂Ti₂ alloy remained almost unchanged even after annealing for 720 ks at 573 K and good wear resistance against S50C steel was also maintained for the extruded alloy tested at sliding velocity of 0.5 to 2 m/sec. These mechanical properties are promising for the future extension of the new Al-based alloys to practical materials. This article is based on a presentation made in the symposium “The 3rd KIM-JIM Joint Symposium on Advanced Powder Materials”, held at Korea University, Seoul, Korea, October 26–27, 2001 under auspices of The Korean Institute of Metals and Materials and The Japan Institute of Metals.     

Effects of cryogenic treatment on the thermal physical properties of Cu<Subscript>76.12</Subscript>Al<Subscript>23.88</Subscript> alloy

The thermal diffusion coefficient,heat capacity,thermal conductivity,and thermal expansion coefficient of Cu76.12Al23.88 alloy before and after cryogenic treatment in the heating temperature range of 25°C to 600°C were measured by thermal constant tester and thermal expansion instrument.The effects of cryogenic treatment on the thermal physical properties of Cu76.12Al23.88 alloy were investigated by comparing the variation of the thermal parameters before and after cryogenic treatment.The results show that the variation trend of the thermal diffusion coefficient,heat capacity,thermal conductivity,and thermal expansion coefficient of Cu76.12Al23.88 alloy after cryogenic treatment was the same as before.The cryogenic treatment can increase the thermal diffusion coefficient,thermal conductivity,and thermal expansion coefficient of Cu76.12Al23.88 alloy and decrease its heat capacity.The maximum difference in the thermal diffusion coefficient between the before and after cryogenic treatment appeared at 400°C.Similarly,thermal conductivity was observed at 200°C.     

自生复合Cu-Cr合金综合性能的热稳定性

研究了用于电车线材料的自生复合Cu Cr合金的综合性能及其热稳定性。实验表明 :自生复合Cu Cr合金不仅在室温下具有优良的综合性能M指标 (σ2b·σr) ,而且还具有良好的热稳定性。室温下 ,自生复合Cu Cr合金线的综合性能可高达 18.3× 10 6MPa2 · % ,高于目前所知各种铜合金电车线 ;而在 5 0 0℃ ,3h加热保温条件下 ,自生复合Cu Cr合金的综合性能仅下降 3%。同时分析了自生复合合金热稳定性与强化机制的关系     

添加铝对AlNp/Cu复合材料组织与热性能的影响

为提高高体积分数AlNp/Cu复合材料的致密度,采用粉末冶金液相烧结工艺制备了含10vol%Al的AlNp/Cu复合材料,与未添加Al的AlNp/Cu复合材料以及AlN颗粒表面镀铜的AlNp/Cu复合材料进行了组织与热性能的比较.X射线衍射与显微组织观察表明,添加的Al在烧结过程中扩散至铜基体形成固溶体,并能有效的提高AlNp/Cu复合材料的致密度,添加10vol%Al的复合材料相对密度与未添加Al的AlNp/Cu复合材料相比提高了3.5%.热膨胀试验表明:50～550℃之间,40% AlNp/Cu复合材料、添加10vol%Al的40%AlNp/Cu复合材料及AlN颗粒表面镀铜的40%AlNp/Cu复合材料的平均热膨胀系数分别为15.7、13.4和13.4,热循环后的残余应变分别为0.51%、0.18%和0.24%.Al的添加及AlN颗粒表面镀铜都能有效地降低AlNp/Cu复合材料的热膨胀系数和热循环后的残余应变.与表面镀铜的AlNp/Cu复合材料相比,Al的添加在一定程度上降低了AlNp/Cu复合材料的热传导性能,但材料的制备成本显著降低.     

Crystal structure and thermal stability of martensite in Cu-25Al-3Mn alloy

The martensite structure in Cu-25Al-3Mn alloy and its thermal cycling and aging behavior are studied. It is convinced that the M2H martensite can be obtained by water-quenched, and the atoms distribution on the basal plane of the mart ensite is: Ⅰ(corner)-Al; Ⅱ(center of the plane)-Cu; Ⅲ(middle of b- side)-22/25Cu+3/25Mn. The lattice parameters are determined to be a=0.445 9 nm, b=0.527 9 nm, c=0.424 1 nm, β=88.64°. The triangle and other complicated configurations consisting of the variant group in the martensite are discovered. It is showed that the tested alloy has a high thermal stability when aging at average temperature in the parent phase, and the thermoelastic martensite amount is up to 90% af ter aging for 96 hat 400 ℃. The thermal cycling has a little influence on the transform ation temperature (Ms). When the number of thermal cycles is up to 1000, the increasing of Ms is only 8 ℃.     

压力浸渗法制备Si_3N_(4p)/2024Al复合材料的时效和热膨胀行为(英文)

采用压力浸渗法制备Si3N4p/2024Al复合材料,并研究其时效和热膨胀行为。2024铝合金和Si3N4p/2024Al复合材料的峰时效时间及硬度均随着时效温度的升高而降低。激活能计算结果表明,在Si3N4p/2024Al复合材料中s′相析出比在2024铝合金中容易。Si3N4的加入,未改变析出相的析出顺序,但是加速了析出。在低于100℃时,Si3N4p/2024Al复合材料的热膨胀系数接近Kerner模型(即Schapery模型的上限)和Schapery模型的下限的平均值。由于低的内应力、弥散分布的Al2MgCu析出相对位错的强钉扎作用以及高密度缠绕的位错,时效处理后的Si3N4p/2024Al复合材料具有最好的尺寸稳定性。由于具有良好的力学性能和钢匹配的热膨胀数系以及优异的尺寸稳定性,Si3N4p/2024Al复合材料在惯性导航领域具有广阔的应用前景。     

Mechanical properties of rapidly solidified Al-Ti alloys after thermal exposure

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｌｕｍｉｎｉｕｍａｌｌｏｙｓｒｅｉｎｆｏｒｃｅｄｗｉｔｈａｌｕｍｉｎｉｄｅｐａｒ ｔｉｃｌｅｓ (ＮｉＡｌ3,ＦｅＡｌ3,ＺｒＡｌ3,ＴｉＡｌ3,ｅｔｃ) ｐｏｓｓｅｓｓｈｉｇｈｓｐｅｃｉｆｉｃｓｔｒｅｎｇｔｈ ,ｈｉｇｈｓｐｅｃｉｆｉｃｍｏｄｕｌｕｓａｎｄｅｘ ｃｅｌｌｅｎｔｐｒｏｐｅｒｔｉｅｓｂｏｔｈａｔａｍｂｉｅｎｔａｎｄｅｌｅｖａｔｅｄｔｅｍ ｐｅｒａｔｕｒｅ[1～ 6 ] .Ｃｏｍｐａｒｅｄｗｉｔｈｍｏｓｔｏｔｈｅｒａｌｕｍｉｎｉｕｍ ｒｉｃｈｉｎｔｅｒｍｅｔａｌｌｉｃ ,Ａｌ3Ｔｉｉ…     

热处理对Cu-Cr(-Zr)合金力学性能和导电性能的影响

制备了Cu Cr和Cu Cr Zr二种合金板材 ,研究了不同热处理工艺对合金的显微组织、力学性能和导电性能的影响。结果表明 ,在本实验条件下 ,Cu 0 .5Cr合金经 960℃ ,1h固溶和 450℃ ,2 0h时效后 ,抗拉强度为363MPa,屈服强度为 2 74MPa ,延伸率为 2 2 % ,电导率达 81 %IACS ;添加微量Zr到Cu 0 .5Cr合金中 ,在不降低合金延伸率情况下 ,合金强度可提高 50MPa,但电导率降低约 1 0 %IACS。     

SiC_p/Al基复合材料的铝浴自蔓延反应制备及其热学性能

将SiC和Ti的混合粉末压坯浸入铝液中 ,引发SiC和Ti的自蔓延反应 ,制备了低膨胀、高导热和高含量SiCp/Al基复合材料。自蔓延反应产物Ti5Si3和TiC在SiC颗粒表面原位形成涂层 ,改善了SiCp/Al界面的润湿性。SiC颗粒自重沉降 ,可形成高SiC含量的复合材料。考察了复合材料的热膨胀系数、导热系数及其与自蔓延反应之间的关系。结果表明 ,自蔓延反应对材料的热膨胀系数影响不大 ,但剧烈的自蔓延反应会损害材料的导热性能 ,如果适当控制反应程度 ,可以制备低膨胀、高导热的SiCp/Al基复合材料。     

镀TiC金刚石/铝复合材料的界面及热膨胀性能

采用气压浸渗法制备高体积分数的镀TiC金刚石/铝复合材料,通过SEM和EDS等手段对复合材料的断口形貌进行分析,并研究TiC镀层对复合材料界面和热膨胀性能的影响。结果表明:TiC镀层改善金刚石颗粒与铝合金基体之间的选择性粘结现象,断裂方式以基体断裂为主。部分TiC会被氧化成TiO2并与铝合金基体反应生成Al2O3,从而实现金刚石颗粒与铝合金基体之间良好的界面结合;TiC镀层有效地降低复合材料的热膨胀系数(CTE),增强复合材料热膨胀性能的稳定性。在体积分数相同的情况下,CTE随金刚石颗粒尺寸的减小而减小。     

Crystal structure and thermal stability of martensite in Cu-24Al-3Mn alloy

1　ＩＮＴＲＯＤＵＣＴＩＯＮＣｕ ｂａｓｅｄｓｈａｐｅｍｅｍｏｒｙａｌｌｏｙｓ (ＳＭＡ )ｗｅｒｅｓｔｕｄｉｅｄｂｙｍａｎｙａｕｔｈｏｒｓｉｎｒｅｃｅｎｔｙｅａｒｓ[1～ 13 ] .Ｉｔｉｓｃｏｎｖｉｎｃｅｄｔｈａｔｔｈｅｓｈａｐｅｍｅｍｏｒｙｅｆｆｅｃｔｉｓａｓｓ     

热处理对Fe-36Ni因瓦合金箔热膨胀及力学性能的影响

研究了60 μm厚Fe-36Ni因瓦合金箔冷轧态、退火态及淬火态的热膨胀行为及力学性能演变规律和作用机理。结果表明,冷轧态合金具有最小的热膨胀系数,淬火态次之,退火态热膨胀系数最大;热处理可有效提高合金的居里温度T_c,从而增大使用温度范围,900 ℃保温1.5 h淬火试样具有最优的热膨胀性能($\bar{α}$_{(20-100 ℃)}=1.02×10^-6 K^-1,T_c=276 ℃),自由取向晶粒的增加是导致合金热膨胀系数增大的原因。与冷轧态相比,热处理后合金发生完全再结晶,并产生退火孪晶伴随有晶粒尺寸的变化和∑3ⁿ晶界比例快速升高,其中800 ℃保温1.5 h淬火试样的晶粒最细小(6.6 μm),∑3ⁿ晶界占比最高,具有最高的屈服强度(267 MPa)和抗拉强度(414 MPa)。淬火处理试样的综合性能优于退火试样。相同热处理方式下,升高热处理温度,一方面降低热膨胀系数,提高居里温度;另一方面也降低了强度。     

Cu-Cr合金在H_2-H_2S混合气中的腐蚀行为

研究了Cu Cr合金及纯铜、纯铬在 5 0 0～ 60 0℃ ,硫分压为 10 -5Pa时的硫化腐蚀。两种Cu Cr合金的腐蚀速度均介于两种纯金属之间 ,并随温度的升高而增大 ,但在两种Cu Cr合金的表面均形成了复杂的腐蚀产物膜 ,外层为Cu2 S层 ,有时不连续甚至剥落 ,中间层为二元Cu Cr硫化物CuCrS2 ,内层为二元Cu Cr硫化物Cu Cr2 S4和CrS的混合物 ,有时也包含未被腐蚀的金属铬颗粒。在腐蚀区以下的合金基体中没有铬的贫化现象发生。这种腐蚀膜结构的形成是合金中存在两相的结果     

Microstructure evolution,mechanical properties and tailoring of coefficient of thermal expansion for Cu/Mo/Cu clad sheets fabricated by hot rolling

The law of microstructure evolution and mechanical properties of hot roll bonded Cu/Mo/Cu clad sheets were systematically investigated and the theoretical prediction model of the coefficient of thermal expansion (CTE) of Cu/Mo/Cu clad sheets was established successfully. The results show that the deformation of Cu and Mo layers was gradually coherent with an increase in rolling reduction and temperature and excellent interface bonding was achieved under the condition of a large rolling reduction. The development of the microstructure and texture through the thickness of Cu and Mo layers was inhomogeneous. This phenomenon can be attributed to the friction between the roller and sheet surface and the uncoordinated deformation between Cu and Mo. The tensile strength of the clad sheets increased with increasing rolling reduction and the elongation was gradually decreased. The CTE of Cu/Mo/Cu clad sheets was related to the volume fraction of Mo. The finite element method can simulate the deformation and stress distribution during the thermal expansion process. The simulation result indicates that the terminal face of the clad sheets was sunken inward.     

Cu-Zn合金高压热处理后的组织演化及热膨胀性能

利用膨胀仪测试了Cu-Zn合金高压热处理前、后在25～700℃的热膨胀系数;采用金相显微镜﹑X射线衍射仪及差示扫描量热分析仪对Cu-Zn合金高压热处理前、后的组织进行研究;探讨高压热处理对Cu-Zn合金的组织及热膨胀性能的影响。结果表明：高压热处理能细化Cu-Zn合金的组织,增大Cu-Zn合金的热膨胀系数,同时,也能使Cu-Zn合金的热膨胀系数在α-T曲线上出现高峰值,且压力越大,热膨胀系数峰值越小。