A.R. Kiani-Rashid
材料科学技术(英文)
The purpose of this study was to determine the influence of heat treatment cycle on graphite phase formation on CK 45 steel. The presence of well distributed graphite in the matrix is responsible for the good mechanical and thermal properties of this kind of alloy. Such properties include excellent wear resistance, higher resistance to thermal shock, and higher resistance to oxidation at high temperature. A number of specimens were made up of appropriate design to provide the experimental materials. The transformation phase to a free carbon microstructure during graphitization under different conditions was then examined for the most successful experimental steels. Austenitising temperature of 920°C and the following isothermal heat treatment of 750°C at different holding times were used. Microstructures were examined by OM (optical microscopy) and SEM (scanning electron microscopy). Furthermore, it was found that isothermal transformation at 750°C for different soaking times produced a typical microstructure. Also, the amount of graphite increased with increasing isothermal heat treatment time. Heat treatment leading to supersaturation of iron with carbon was described and some of the consequences of the supersaturation were presented. Finally, the formation of the thermodynamically stable state of the graphite taken from the supersaturated solid solution was discussed.
关键词:
Graphitization
张祖力
,
王华
功能材料
N型热电偶是为了提高K型热电偶性能而研制出的一种综合性能更好、更稳定的热电偶,它在K型热电偶的基础上对其抗氧化性能、辐照嬗变、有序无序转变和磁性转变等方面进行了改进,从而提高了热电稳定性能及抗高温氧化性能.
关键词:
N型热电偶
,
K型热电偶
,
热电稳定性
Ata Kamyabi-Gol
钢铁研究学报(英文版)
When processing parts made from medium carbon steel, toughness and flexibility are of importance. Therefore, to achieve these properties, the cementite in the steels is spheroidized through heat treatment. Different parameters such as the time and temperature of spheroidizing and the initial microstructure of the steel affect the amount of spheroidized cementite. In the present work, the percent of contribution of two parameters, i.e. initial microstructure and spheroidizing time, on the percent of spheroidization in CK60 steel was investigated using Taguchi robust design. Based on the number of parameters (two) and the number of their levels (four), a L16 orthogonal array, which consists of 16 experiments, was chosen. The initial microstructures consisted of Martensite (M), Coarse Pearlite (C. P.), Fine Pearlite (F. P.), and Bainite (B) and the chosen spheroidization times were 4, 8, 12, 16 hours. Spheroidizing was done at the constant temperature 700 oC. After spheroidizing was completed, the samples were prepared in order to view their microstructure under an optical microscope and to determine the spheroidized percent using MIP? (Metallographic Image Processing) software. It was found that the spheroidizing time had the most influence (58.5%) on spheroidized percent and the initial microstructure only had a 31.1% contribution. Finally, the instantaneous growth rate of the carbide was also deduced.
关键词:
Spheroidizing;Kinetics;Heat treatment;CK60;Taguchi
段兴凯
,
胡孔刚
,
丁时锋
,
满达虎
,
林伟明
,
金海霞
稀有金属材料与工程
采用真空熔炼及热压方法制备了Ga和K双掺杂N型Bi2Te2.7Se0.3热电材料.XRD分析结果表明,Ga和K已经完全固溶到Bi2Te2.7Se0.3晶体结构中,形成了单相固溶体合金.SEM分析表明,材料组织致密且有层状结构特征.通过Ga和K部分替代Bi,在300~500 K的大部分温度范围内,Ga和K双掺杂对提高Bi2Te2.7Se0.3的Seebeck系数产生了积极的作用,同时双掺杂样品的电导率也得到明显的提高.Ga和K双掺杂样品的热导率都大于未掺杂的Bi2T2.7Se0.3,Ga0.02Bi1.94K0.04Te2.7 Se0.3合金在500 K获得ZT最大值为1.05.
关键词:
双掺杂
,
热压
,
显微结构
,
热电性能
戢景文
,
魏全金
,
张国福
,
赖祖涵
,
陈廷国
金属学报
研究了F? P—N合金加?对Snoek—Ke-Koster(SKK)峰的影响,发现与合金含La,P的原子浓度比(C_(La)/C_p)有关:对于C_(La)/C_p较大(例如4.56和2.6)的合金,La有明显增强SKK阻?效应:对于C_(La)/C_p=0.27的P过饱和合金,La对SKK峰无明显影响。
关键词:
内耗
,
Snoek-Ke-Koster peak
,
Fe-P-La-N alloy