1、先進(jìn)復(fù)合材料工藝?yán)碚摶A(chǔ) -凝固,主講人：范清松 導(dǎo)師 ：陳善華(教授),提 綱,引言 浸滲凝固過(guò)程溫度場(chǎng) 凝固組織,引 言,復(fù)合材料凝固的重要性： 凝固，是物質(zhì)從液相變?yōu)楣滔嗟南嘧冞^(guò)程，是產(chǎn)生晶核和晶核生長(zhǎng)的過(guò)程。 液相工藝最后一個(gè)環(huán)節(jié)； 不僅影響浸滲過(guò)程，而且決定最終顯微組織； 對(duì)復(fù)合材料性能影響很大。,引 言,復(fù)合材料凝固涉及的問(wèn)題： 凝固過(guò)程溫度場(chǎng)； 凝固組織； 凝固對(duì)性能影響,凝固過(guò)程溫度場(chǎng) 短纖維復(fù)合材料,實(shí)驗(yàn)條件： gas pressure infiltration：3 MPa using oxygen free nitrogen gas ； 0.16 volume fracti

2、on short SAFFIL fibre preforms ； commercial purity aluminium ； temperature from four points within the die, three within the reinforcement preform and one within the non-infiltrated melt,浸滲過(guò)程溫度場(chǎng),Temperature record during casting for (a) CP1 (b), CP2 and (c) CP3 each cast with a fibre volume fraction

3、 of 0.16 and an initial fibre temperature of 450 C, initial melt temperatures where 820, 775 and 675 C, respectively,positions are as depths below the top surface of the preform,凝固過(guò)程溫度場(chǎng),Casting conditions of samples CP1, CP2 and CP3,凝固過(guò)程溫度場(chǎng),Temperature record of the solidification of casting CP1,凝固過(guò)

4、程溫度場(chǎng),Axisymmetric section of casting CP1 (1.2) etched in Tuckers reagent. The white dashed line indicates the axis of symmetry and the white arrows the top of the preform,浸滲過(guò)程溫度場(chǎng) 模擬,the fibres initially at 450 C, 0.2 volume fraction exposed to melt at a 100 C superheat, 760 C. the temperature equili

5、brates very rapidly, 106 s due to the fine scale of the fibre,浸滲過(guò)程溫度場(chǎng) 模擬,Theoretical 3D plot of temperature against time and position within the casting,sample CP1. Temperature is plotted against both time and position within the final casting, a positive depth refers to the composite section of the

6、 casting while a negative depth infers a position within the non-infiltrated excess melt above the reinforced section,浸滲過(guò)程溫度場(chǎng) 模擬,Theoretically calculated temperature plot for castings CP1, CP2 and CP3,凝固過(guò)程溫度場(chǎng) 模擬,高導(dǎo)熱材料和電子封裝材料,HTCM Group,3D temperature/time/depth plot for the solidification of casting

7、 CP1,凝固過(guò)程溫度場(chǎng) 模擬,Theoretical plot for the solidification of casting CP1,凝固過(guò)程溫度場(chǎng) 顆粒復(fù)合材料,Ternary equilibrium diagram Al-Mg-Si,凝固過(guò)程溫度場(chǎng) 顆粒復(fù)合材料,Scheme of the stand for ATD measurements ATD method (analysis of thermal derivative dT/dt ）,凝固過(guò)程溫度場(chǎng) 顆粒復(fù)合材料,Solidification of the AlSi7Mg4 composite matrix: (a) AT

8、D curve, (b) heat source function calculated from the ATD curve (dT/dt); AB-dynamic of solidification of the -phase, CD-dynamic of the eutectic solidification, AC- phase solidification time, CE-eutectic solidification time, AE-composite solidification time, (dT/dt)g-basic (calorimetric) curve,凝固過(guò)程溫度

9、場(chǎng) 顆粒復(fù)合材料,The thermophysical properties of the materials,凝固過(guò)程溫度場(chǎng) 顆粒復(fù)合材料,Influence of the SiC particle content on the kinetics of solidification of the AlSi7Mg4-SiC composites,The ceramic particles introduced into the metal matrix change significantly the kinetics of the composite solidification, decr

10、easing the mass of the solidifying metal by the quantity corresponding to the volume occupied by the SiC particles, and by diminishing the quantity of liberated solidification heat, increasing the heat flow resistance caused by the presence of the particles (SiC Al).,凝固過(guò)程溫度場(chǎng) 顆粒復(fù)合材料,Influence of the

11、SiC particle size on the kinetics of solidification of the AlSi7Mg4-SiC composites,Taking into account the registered course of the cooling curve and its first derivative dT/dt the following points can be determined:,凝固過(guò)程溫度場(chǎng) 顆粒復(fù)合材料,The characteristic points of solidification,凝固組織,Back scattered elec

12、tron image of iron-rich precipitates in casting CP3 taken behind the position of the remelting front at the end of infiltration, i.e. from a region solidifying from a purely liquid matrix,凝固組織,Back scattered electron image of iron rich impurity precipitates in CP1 from below the final position of th

13、e remelting front where solid material formed during infiltration was present prior to final solidification,凝固組織,Microstructures of (a) the metal matrix and (b) the AlSi7Mg4-SiCp composite (20%).,SiC particles retard the growth of the phase,凝固組織,SEM microstructure of the SiCp/matrix interface in the AlSi7Mg4-SiCp composite,The lack of the Al4C3 phase has been also confirmed by electron microscopy,凝固組織,The influence of (a) content and (b) size of SiC particle on the liquidus temperature in AlSi7Mg4-S