用机械合金化方法制备Ni-Al系金属间化合物

用球磨机分别对Ｎｉ－５０ａｔ．－％Ａｌ和Ｎｉ－２５ａｔ．－％Ａｌ混合粉末进行机械合金化，并对Ｎｉ_３Ａｌ预合金粉末进行高能球磨，观察了粉末的金相组织，测定了粉末的硬度、平均直径和晶粒尺寸，并作了ＸＲＤ物相分析结果表明，经３ｈ研磨，Ｎｉ－５０ａｔ．－％Ａｌ混合粉末变成ＮｉＡｌ金属间化合物，其晶粒直径约５ｎｍ；经５ｈ机械球磨，Ｎｉ－２５ａｔ．－％Ａｌ混合粉末成为无序的亚稳定Ｎｉ固溶体，而Ｎｉ_３Ａｌ预合金粉末由Ｌｌ_２型长程有序金属间化合物转变为ｆｃｃ无序固溶体；球磨更长时间，则形成纳米晶．     

预退火处理对非晶Cu-Ti合金晶化过程动力学的影响SCIEI

对非晶Cu_(40)Ti_(60)合金引入一种预退火处理工艺,利用DSC研究了急冷态及预退火处理样品的晶化过程动力学,发现预退火处理使非晶合金的晶化温度、晶化激活能和Avrami指数值下降。由实验结果和理论分析得到了非晶Cu_(40)Ti_(60)合金的形核激活能和长大激活能。     

用机械合金化方法制备Ni-Zr非晶合金

用 Spex 8000 Mixer/Mill 球磨机对 Ni-30at.-%Zr 混合粉末进行机械合金化。观察了粉末的金相组织,测定了粉末的硬度和平均直径,确定了粉末的晶体结构。结果表明,经24h 研磨后,粉末的层状组织消失,成为均匀的单相非晶合金,非晶漫射峰在45°(2θ)附近出现。     

Isothermal Crystallization Kinetics of an Amorphous CuTi Alloy

Isothermal crystallization kinetics ofCu_(40)Ti_(60)amorphous alloy has been studied usingdifferential scanning calorimetry(DSC).Bothas-quenched and pre-annealed ribbons were inves-tigated.For crystallization of as-quenched amor-phous ribbon in Ar,it was found that the kineticsfollows Johnson-Mehl-Avrami equation withmean Avrami exponent n=2.58,which indicatesthat crystallization of amorphous Cu_(40)Ti_(60)is athree-dimensional diffusion controlled growth pro-cess with constant nucleation rate,i.e.,primarycrystallization process.The primary phase is thetetragonal CuTi_2.The as-quenched amorphousribbons were also crystallized in air,the results re-veal that oxidation has no significant influence oncrystallization kinetics of amorphous Cu_(40)Ti_(60).The results of crystallization of pre-annealed rib-bons show a decreasing tendency of Avrami expo-nent with increasing pre-anneal time.The localactivation energy and local Avrami exponent dur-ing crystallization process of as-quenched amor-phous alloy were also examined.     

用机械合金化法制备Sm—Fe合金及其晶化与氮化过程探讨

研究了用机械合金化方法制备的Sm_2Fe_(17)合金的晶化与氮化过程。结果表明:机械合金化的Sm-Fe合金是Sm-Fe非晶相与晶态α-Fe的混合物,其成分是不均匀的,Fe在非晶颗粒外层含量较少,晶化过程包含Fe原子的长程扩散和固相反应,在适当的晶化条件下,晶化后全部转化为Sm_2Fe_(17)相。晶化过程中,可能出现六方结构的Th_2Ni_(17)型Sm_2Fe_(17)亚稳相。氮化过程由孕育期、Sm_2Fe_(17)相与其氮化物相共存、最终全部转化为氮化物相三阶段组成;在氮化过程中有十分细小的少量α-Fe析出。