一项关于一种典型镍基合金中析出物尺寸分布演变的小角X射线散射-小角X射线散射-广角X射线散射研究

An USAXS-SAXS-WAXS study of precipitate size distribution evolution in a model Ni-based alloy.

作者信息

Andrews Ross N, Serio Joseph, Muralidharan Govindarajan, Ilavsky Jan

机构信息

Argonne National Laboratory, USA.

Oak Ridge National Laboratory, USA.

出版信息

J Appl Crystallogr. 2017 May 30;50(Pt 3):734-740. doi: 10.1107/S1600576717006446. eCollection 2017 Jun 1.

DOI:10.1107/S1600576717006446

PMID:28656039

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC5458593/

Abstract

Intermetallic γ' precipitates typically strengthen nickel-based superalloys. The shape, size and spatial distribution of strengthening precipitates critically influence alloy strength, while their temporal evolution characteristics determine the high-temperature alloy stability. Combined ultra-small-, small- and wide-angle X-ray scattering (USAXS-SAXS-WAXS) analysis can be used to evaluate the temporal evolution of an alloy's precipitate size distribution (PSD) and phase structure during heat treatment. Analysis of PSDs from USAXS-SAXS data employs either least-squares fitting of a preordained PSD model or a maximum entropy (MaxEnt) approach, the latter avoiding definition of a functional form of the PSD. However, strong low- scattering from grain boundaries and/or structure factor effects inhibit MaxEnt analysis of typical alloys. This work describes the extension of Bayesian-MaxEnt analysis methods to data exhibiting structure factor effects and low- power law slopes and demonstrates their use in an study of precipitate size evolution during heat treatment of a model Ni-Al-Si alloy.

摘要

金属间γ'析出相通常会强化镍基高温合金。强化析出相的形状、尺寸和空间分布对合金强度有至关重要的影响，而它们的时间演变特性决定了高温合金的稳定性。联合超小角、小角和广角X射线散射（USAXS-SAXS-WAXS）分析可用于评估合金在热处理过程中析出相尺寸分布（PSD）和相结构的时间演变。从USAXS-SAXS数据进行PSD分析时，要么采用预定PSD模型的最小二乘拟合，要么采用最大熵（MaxEnt）方法，后者无需定义PSD的函数形式。然而，晶界的强低散射和/或结构因子效应阻碍了对典型合金的MaxEnt分析。本文描述了将贝叶斯-最大熵分析方法扩展到表现出结构因子效应和低幂律斜率的数据，并展示了它们在研究一种典型Ni-Al-Si合金热处理过程中析出相尺寸演变中的应用。