意大利重骑——重装甲型“公羊”坦克

二十世纪八九十年代,意大利装甲力量开始迅猛发展,它已建立起完整的陆军装备体系。二十世纪八十年代初期,意大利军方决定建立快速反应部队,并研制出相应的新型装备。1982年,意大利议会批准了＂陆军再装备计划＂,国防预算大幅度提高。     

Fe-Zn phase formation in interstitial-free steels hot-dip galvanized at 450°C: Part I 0.00 wt% Al-Zn baths

Interstitial-free alloy steels containing various combinations of solute additions of titanium, titanium + niobium and phosphorus, were hot-dipped in a pure zinc (0.00 wt% Al) at 450°C in order to study the morphology and kinetics of Fe-Zn phase formation. Uniform attack of the substrate occurred on all of the steels leading to the formation of a three-phase alloy layer morphology containing gamma, delta and zeta Fe-Zn phases. Titanium and titanium + niobium solute additions had no effect on the growth kinetics of any of the Fe-Zn phases. Phosphorus additions were found to retard only the kinetics of gamma-phase growth, without influencing the growth kinetics of the other Fe-Zn phases. In fact, the gamma-phase layer in the phosphorus-containing substrates was no longer discernable in light optical microscopy after 120 s immersion. The growth kinetics of the total Fe-Zn alloy layer (gamma + delta + zeta) was dominated by the growth of the zeta-phase layer which was in contact with liquid zinc during immersion in the zinc bath. The zeta-phase layer followed a two-stage growth process governed by t1/3 kinetics. The delta-phase layer also exhibited two-stage growth with parabolic t1/2 kinetics. The gamma phase followed t1/4 growth kinetics, indicative of grain-boundary diffusion-controlled growth. This revised version was published online in November 2006 with corrections to the Cover Date.     

HPLC Determination of Erythorbate in Cured Meats

Erythorbate was measured in nitrite-cured meats using ion-paired HPLC. With tetrabutylammonium formate as the ion pair, good separations were obtained with a linear response' up to 300 ppm of erythorbate. Recoveries were complete and agreed with values obtained by titration with 2,6-dichloroindophenol. The method is specific and free from interferences from other reducing substances in cured meats. Erythorbate and its isomer, ascorbate, are not distinguished under these conditions.     

Phase Transformations and Microstructural Evolution of Mo-Bearing Stainless Steels

The good corrosion resistance of superaustenitic stainless steel (SASS) alloys has been shown to be a direct consequence of high concentrations of Mo, which can have a significant effect on the microstructural development of welds in these alloys. In this research, the microstructural development of welds in the Fe-Ni-Cr-Mo system was analyzed over a wide variety of Cr/Ni ratios and Mo contents. The system was first simulated by construction of multicomponent phase diagrams using the CALPHAD technique. Data from vertical sections of these diagrams are presented over a wide compositional range to produce diagrams that can be used as a guide to understand the influence of composition on microstructural development. A large number of experimental alloys were then prepared via arc-button melting for comparison with the diagrams. Each alloy was characterized using various microscopy techniques. The expected δ-ferrite and γ-austenite phases were accompanied by martensite at low Cr/Ni ratios and by σ phase at high Mo contents. A total of 20 possible phase transformation sequences are proposed, resulting in various amounts and morphologies of the γ, δ, σ, and martensite phases. The results were used to construct a map of expected phase transformation sequence and resultant microstructure as a function of composition. The results of this work provide a working guideline for future base metal and filler metal development of this class of materials. An erratum to this article can be found at     

Fe-Zn phase formation in interstitial-free steels hot-dip galvanized at 450°C: Part II 0.20 wt% Al-Zn baths

The effect of solute additions of titanium, titanium and niobium and phosphorus on interstitial-free steels on Fe-Zn phase formation after immersion in a 0.20 wt% Al-Zn bath was studied to determine the morphology and kinetics of the individual Fe-Zn phases formed. These results were contrasted to the previous study using a pure zinc (0.00 wt% Al) bath in Part I. It was found that in the 0.20 wt% Al-Zn bath, an iron-aluminide inhibition layer prevented uniform attack of the steel substrate. Instead, localized Fe-Zn phase growth occurred, termed outbursts, containing a two-phase layer morphology. Delta-phase formed first, followed by gamma-phase. Zeta-phase did not form in the 0.20 wt% Al-Zn bath, in contrast with zeta-phase formation in the pure zinc bath. As in the pure zinc bath, the growth kinetics of the total layer was controlled by the Fe-Zn phase in contact with the liquid zinc during galvanizing. For the 0.20 wt% Al-Zn bath, the Fe-Zn phase in contrast with the liquid zinc was the delta-phase, whereas the zeta-phase was in contact with liquid zinc in the pure zinc bath. The delta-phase followed t1/2 parabolic growth, while the gamma-phase showed essentially no growth after its initial formation. Titanium and titanium + niobium solute additions, which enhance grain-boundary reactivity, resulted in more rapid growth kinetics of the gamma- and delta-phases. Phosphorus additions, which decrease grain-boundary reactivity, generally increased the incubation time and retarded the growth rate of the gamma-phase. These results further confirm the concept that solute grain-boundary reactivity is primarily responsible for Fe-Zn phase growth during galvanizing in a liquid Zn-Al bath in which an iron aluminide inhibition layer forms prior to Fe-Zn phase formation. This revised version was published online in November 2006 with corrections to the Cover Date.